The encounter (if that's the right word) between Thor and hammer seems to be awkward and personal, and Jason wonders if he's supposed to not watch. There are a lot of other things to look at, from his growing hat collection to all the people around them. But nobody seems to be in immediate danger, or immediately dangerous. He gives the Hello Kitty hat to a small, miserable child who has stopped talking because tiny frogs fall out of her mouth every time she speaks, which at least seems painless for all parties involved. He keeps his eye on Thor throughout, and once the child has wandered off, hat jammed down low over her eyes, goes back to watching.

Why reluctant? It seems to be more than uncertainty in his strength. (Across the street, the little girl scowls and spits frogs at her brother, who shrieks.)