It's not a huge issue, because only the top-shelf potential draft picks do more good than harm by doing it.
If you play for a team in the College Football Playoff, you are playing, because you want to win a championship. If not, NFL teams wonder about why you play at all, right?
If you play for a team in a "normal" bowl game, you probably have to be a lock for the first round in order to help yourself by not playing. For most NFL hopefuls, the bowl games are a chance to put another game on film with a lot of eyes on it, against good opponents.
It can help bump a guy up a draft board just as much as it can risk getting him hurt
Lock is one of the guys who you can make a case for sitting out. Just don't try to convince him of that. He didn't even think about not playing.