Actually no, he shouldn't.
Bonnar has nothing but a lottery ticket in this fight. On the ground, Silva might actually be careful, he will never submit Silva. Anderson will just work to stand up and make sure he doesn't get in any really bad positions.
Bonnar has next to no chance on the feet, but at least he could win with a Hail Mary shot, I think he has even less chance of a Hail Mary sub.