Bilbo doesn't need to stay in the thick of the company, and he'd much rather stay with Thorin. Yet, it would be expected of him to stay in the middle and so that is what he does, careful to look wide eyed when the company finds Erebor empty of all but gold covering layers of skeletal remains of men, women and children that had not escaped the onslaught.

It's a difficult time for everyone save Thorin's nephews and Bifor, Bofur and Bombur, whom have never lived here. The rest however--

Bilbo pushes his way to the front, to the throne, to where Thorin stands.

"It doesn't look as if he's taken a thing."