I didn't say he needs to gain weight. I'm saying that if he was doing SS, actually lifting with intensity, and eating properly, there would be no reason to be stalled at a 175 bench press. Which means 1 of those 3 components is missing. If I assume he's following the program properly, this leaves intensity and diet. I think diet is the more likely culprit.
EDIT: a fourth possibility is that OP is female. That would make a difference.
Also, please note that in his first post he mentioned he's 'on a bulk'. So he clearly wants to gain weight.