Welcome to Librarium Online!
Unless I'm missing something, it seems like TS can actually hurt your chances of wounding in certain cases.
For example, if a Prime with both TS and AG assaults will he wound MEQ on a 4+ with re-rolls of 4+ (75%) because of toxin sacs instead of on a 2+ (83%) because of AG?
It seems like the rules state that it must be the former, which is odd because it means that TS reduce your chance to wound.
Correct. TS on high S models makes them worse against low T models.