You only beats bluff, so yes it is a hero call, but its not that many hands he can have here. Because most of the pairs he will check on the river. So you are afraid of two pairs, sets or AK/AA. This is a freeroll as well, so there are many players who are bluffing.
But I donīt like the call pre, it is to early in the tourney, and not worth calling with 107 (even in position). When you do call, I would have raised the flop, just to narrow his range.