It's bruises to the chest and shoulder, not the face, so he can still grunt,

"Stupid--idiot--That's just going to--make someone want payback--"

He would really like Bakugou to be more considerate of others, if only for the sake of not having to reap what he sows and getting people (Midoriya) caught in the crossfire! On multiple occasions it's been jumping into stuff, mouthing off... mostly mouthing off...

This calls for a desperate measure: an accomplice.

He pivots away from the worst of the blows, moving his feet around rather than through the indomitable wall of anger, spite, and shame that is Katsuki Bakugou, walking disaster. Uraraka would be proud, but it's still difficult to prevent himself from colliding in a jumble with the door while struggling. He bashes his hand against the lock, fumbles, and it clicks open. He calls through the door,

"Sorry! We're coming out! Could you cover your eyes? This is really embarrassing!"

Under his breath in a mutter as he works the knob, "Gotta--make sure--he does--Don't you dare, Kacchan--"