If scientests could have been smart enough to figure out how to engeneers HIV, they probably would have had enough brain cells to realise it sucks as a bio-weapon.

Biological weapons kill or disable quickly, so they have to be disseminated quickly and easily. They don't travel around and wind up in your, or your allies' countries, and you damned well better have some form of vaccine or cure for your own selves before you let them out.

I don't think taking advantage of a pre-existing population-culling disease is beyond some folks though. No, I KNOW it's not beyond them. I've met enough morons who've said something like "It only kills them junkies, whores and hummasekshuls, and them bastards had it comin'! The lord done SMOTE them with his wraths!" I guess they think all those babies, infected transfusion recipients, and heterosexual partners of Bad People had it coming too. I don't supposed it's beyond the realm of possibility for stupid and vengeful to get in a position where all they have to to kill people was ignore the problem.