Unfriendly introvert, meet unfriendly introvert. Create space paradox.

[ he makes a gesture with his fingers--kaboom. ]

And the same reason he gets upset about anything about this planet that's different from back home.
It messes with his sense of survivability.

Worms are a quick and easy thing to grab and eat in a bad situation.
He's here and he's got a home with more food than he'll ever know what to do with.

But the idea that something he's used to surviving on is changed here--or unavailable--makes him nervous.