I am not sure if it is that easy in this case. We're used to the child citizenship act, which is pretty clear and makes applying for a U.S. passport really easy. However, his case is a bit less straightforward (from the point of view of passport). It seems the rule that applies here is to have a green card and having regularly resided. I believe this makes applying for a passport under this rule tougher or impossible. I don't even see this case in the passport application (which on the other hand covers the child citizenship act alright). Actually, the instructions on the passport are not clear, as they don't specify the time when the CCA (child citizenship act) was applicable, and they just asked for certificates of naturalization and green card.
My gut feeling is that TNM99 needs to apply for N-600 first, before trying to apply for a passport, if this is possible. I think TNM99 can have a reasonable belief and certainty in being a citizen, but the certificate of citizenship will be a real proof.
I believe it all hangs on that little condition (which I guess TNM99 complies, but USCIS needs to document and verify) that he needed to regularly reside in the U.S. after obtaining the Green Card.
PS: Please let me point out that TNM99 seems to qualify to apply with N-600, that doesn't mean that he is an automatic citizen. I keep claiming that I am a bit ignorant about what happened before the child citizenship act. I am not sure whether citizenship was granted automatically or not when the parents naturalized. I really believe that N-600 is probably the best route, but if N-600 is taking a long time at TNM99's local USCIS office, perhaps N-400 could be good. These things get so complicated that I doubt many people at USCIS can keep things straight either. It would have been good that the N-600 instructions pointed to the applicable law. I haven't been able to find information about people whose parents naturalized when they were minors and before the CCA. By the way, I think I've seen the "magic" number 16 years a few times, I am not sure if it applies to pre-CCA cases.
Probably one of these cases mentioned here is the one that applies to TNM99:
http://tinyurl.com/2j29oa