It doesn't, really, he's just caught up in overthinking everything and being a petty motherfucker and seeing how much of Optimus' time he can waste. It's fun to see the different levels he can push at. Regardless, if Optimus wants to think he's a dumbass he doesn't care enough to try to convince him otherwise.

"One of many, no doubt."

See that? That right there is Sentinel just straight up not giving a shit about whatever skills any of them might have had. IF HE WAS SO SMART WHY WAS HE BORN INTO THE MINING CASTE?????