I think this is going to be written off as an individual nutjob. The guy's term of service was 1992 to 1998. Ending his active duty service prior to 9/11 might mean he did not get any intel on the differences between Sikh and Muslim, but you would think someone non-retarded would commit to an attack for an articulated reason.
I can't fathom what happens in the mind of every cockroach just to put a conspiracy theory spin on it, all I can say at this point is that it was not our guy who did this. Whatever his "ties" are to some Neo-Nazis I am sure will get looked at, but those groups tend to attract a lot of flotsam and jetsam anyway. It is entirely possible that they had disassociated him also.