If Milano doesn't make a huge play on the first 2PC, then the second TD would have been a PAT for the lead, forcing Buffalo to have to go down the field to win. Maybe they do, maybe they don't.
If the Bills had done the obvious tush push (or two) on 3rd and goal from the 2, then this wouldn't have been an issue because they'd have 31 points instead at the end (or 30 with a shanked PAT), in which case the Ravens would have been forced to onside kick regardless.
The Bills were taking shots downfield in addition to establishing the run to keep the defense honest in the first half and came out of it with 21 points. In the second, they only did short passes literally the entire time, which allowed the Ravens D to tighten and cause Buffalo to score 6 points and making it a game.
Yes, yes it did almost cost them.