Should I reward points for an incorrect answer if it is the result of misinformation presented in a TA's office hours?
I agree that in principle, the student is responsible for critically evaluating information from all sources and rejecting any that's incorrect.  I wouldn't simply award the student points for the incorrect solution, but on the other hand it seems unhelpful to just mark it wrong and leave it there (and despite your explanation, the student will likely perceive this as unfair).  In similar situations, I've done one of two things:


Allow the student to revise the answer, and regrade the problem; or
Discard the problem for that student, and recompute the score for the assignment based only on the remaining problems.