Through an effort of will (and prepared bracing), Jason remains both upright and silent, instead of uttering a very dignified 'hurk'. Regardless of resolve, however, Jason does take a hasty step back when Thor — exclaims, that wasn't really a shout, Jason has heard him shout — about the hammer. It's not about nerve, it's just being pragmatic. Besides, Thor did just say 'little gods' and while Jason isn't entirely sure about how much he believes in the active intervention of various divinities, it seems like a straightforward guess that Thor just tried to leave and they or Vague Forces of Stuff backhanded him right back down. Maybe it'd be best to stand aside.

"Over there." He points, and then pulls off his current hat because it's soaked. What the hell is that. The new hat has a wider brim, which is useful, at least. And hopefully it doesn't have a penis or a swastika on top. (It doesn't.)