Maybe Steve didn't want the sorry, that was true, but Tony felt like he needed to give it. At least a little bit, Because he'd never really apologize verbally, not when he stood firm on his opinion that what he'd done -- what he would do (maybe. If they ever got there) -- was the right move and only choice.
But he could be dissuaded from saying too much in just a kiss, maybe. Particularly when Steve was practically picking him up, and it had Tony's mind blanking almost completely from anything that wasn't in the now. He used the door behind him as an anchor support, and had his legs wrapped around Steve's hips like climbing him was a hobby he'd practiced and mastered forever ago instead of this being the very first time.
"I came," he said, even though he knew talking would probably ruin it, would break whatever spell was happening here. "I'm here." And that had to mean something, that Steve had asked, and Tony had listened. He could do that here, even if he'd left him alone and behind somewhere else.