well, you have to break dwn the issue, was his i 485 approved?, or not, has his name check finshed or not?, is there a final name check result, and if so is there negative information on his file,?
fbi finish the name check then send it to uscis, who evaluate the fbi reprot, and make a decision to grant or deny the benefit, or the petition, this is different that the delay any one might experience because his/her name check is still pending which that they dont have it yet, and still waiting for the fbi to finish it.
if your husband name check is finished, then the uscis will make one of two decisions, keep the file on hold for further investigation,or make a decision to grant or deny the application.
but when you say the he " cant get his passport stamped, due to security clearence pending" you have to explain if he have already been approved as "a permanent resident" a case in which they have to stamp his passport, and give him his green card, or you have to explain ih his adjustmet of stutus still pending because his name check , security clearence is not finishe yet, which mean they have not approved, or denied the application they are simply still waiting for the result of thename check.