Early last year, I had my own federal case and so I recall reading a bunch of cases with delayed/denied citizenship and this case was a part of that. It was not particularly relevant to me so I didn't keep the citation. But in general, the materiality standard in immigration law is governed by the Supreme Court decision in Kungys v United States. This decision also governs the "good moral character" requirement specifically pertaining to lying and what specific lies would bar GMC (further elaborated by Maslanjak v US in 2017). Any case involving materiality or GMC either by BIA or federal courts always uses the Kungys "natural tendency" test. You could read the case but just to give a gist I am copying a summary of facts from Lexis.
In October 1944, Kungys and his wife moved to Tuebingen in Nazi-occupied Germany where they lived under an unrestrictive residence permit that allowed them to move freely throughout the territory without special conditions. In January 1947, they applied for a United States non preference immigration visa at the American consulate in Stuttgart, Germany. Although the records in Tuebingen accurately stated Kungys' true date and place of birth, Kungys submitted a false Lithuanian identity card, false birth certificate, false police certificate, and a certificate stating that the Gestapo had persecuted him. Based on this information, the American consulate *451 issued Kungys a non-preference visa in March 1948. Kungys became a naturalized citizen in Newark, New Jersey, in 1954.
The government moved to de-naturalize him that he had materially misrepresented his date of birth, place or birth and wartime occupation during his immigrant visa and naturalization application and hence his naturalization was illegally procured.
In determining whether Kungys' misrepresentations met the Court's new standard of materiality, the Court held that � 340(a) is limited to falsehoods or deceptions in the naturalization proceedings and not misrepresentations made in the visa process, because it is the former falsehoods which "procure" the naturalization. The Court concluded that Kungys' misrepresentations of the date and place of his birth in his naturalization petition were not material. There was no suggestion that the facts were themselves relevant to Kungys' qualifications for citizenship. Likewise, there was no showing that the true date and place of birth would have disclosed other facts relevant to his qualifications and would have resulted either in outright denial or an investigation resulting in denial of the naturalization application. Hence, the government failed to establish clearly, unequivocally, and convincingly that Kungys' misrepresentations had a natural tendency to influence the decision of the INS.
For purposes of determining the natural tendency of a misrepresentation to affect a decision under § 1451(a), what must have a natural tendency to influence the official decision is the misrepresentation itself, not the failure to create an inconsistency with an earlier misrepresentation.
A misrepresentation is generally material only if by it the individual received a benefit for which she would not otherwise have been eligible. See Kungys v. United States, 485 U.S. 759 (1988); see also Matter of Tijam, 22 I&N Dec. 408 (BIA 1998); Matter of Martinez-Lopez, 10 I&N Dec. 409 (A.G. 1964; BIA 1962). A misrepresentation or concealment must be shown by clear, unequivocal, and convincing evidence to be predictably capable of affecting, that is, having a natural tendency to affect, the official decision in order to be considered material. Kungys at 771:...72.
In Cufari v. United States (1st Cir.1954) the First Circuit held that a naturalized citizen could not be denaturalized for failing to disclose his criminal record at the time of naturalization, unless the government could prove that he had been asked during the proceedings whether he had a criminal record and that he had answered in the negative.
Again, I am not a lawyer but I think a lawyer can make an argument that the claim of being married or single is statutarily irrelevant for the B1/B2 visa since there is no statute or regulation that governs the grant or denial of such a visa based on marriage. B1/B2 visas are routinely granted to both married/single and divorced individuals. Whether the argument is successful or not depends on the judge and the government's counter argument where they have to show that had they known that the applicant was single, the visa would have been denied or it would lead to a line of inquiry that would have led to disqualifying facts.
However, like I said the biggest problem is to prove that OP was not married before. The burden of proof is on OP as this would make his current marriage a bigamy (if not divorced) which is an expressly disqualifying fact. This opens up a can of worms. Suppose OP has named Jill Smith as his wife on DS160, how can he prove that she was not really is wife during the time and he was really single? Was he lying then or is he lying now? The question of materiality will come into play ONLY AFTER it is proved that OP was actually single and unmarried before he married his current wife. Only after OP proves that he did not engage in a bigamous relationship, then the courts will try to find if his previous misrepresentation was material or not. Hence I agree with @SusieQQQ that based on other cases it will be a tough nut to crack - I am assuming the other cases had a hard time proving the single status in the first place.