Don't vary your bet size based on the strength of your hand. That's why we play ranges and not hands. As long as we aren't giving him the odds to chase draws that's all that matters.
I have absolutely no idea why he's betting $2.25 and not like $3 though. Accomplishes all the goals of the smaller bet whilst getting more money into the pot. Allows him to bluff shove certain hands over the top of us and isn't going to fold out any more of his range imo.