There are so many stupid things about this one tweet.
a) that's not why he was cradling the football. He was about to cross the goal line. Pretty normal.
b) he was on his way to his first NFL TD and wanted to make sure.
c) let's assume it had ANYTHING to do with that: well, Janovich is in his first NFL game and he's a f*ing fullback and has already run 22 yards. NFL running backs RARELY have runs that long and fullbacks almost never do, so of course he was expecting someone to catch up and for it not to really happen. (Except, again, that was not why he was cradling the football).