define a general intelligence as one that doesn't perform stupidly in a novel environment

What does "stupidly" mean in this context?

It also seems to me you're setting up a very high bar, one that you yourself admit (individual) humans generally can't reach. If they can't, why set it so high, then? Since we can't get to even human-level intelligence at the moment, there doesn't seem to much sense in speculating about designing even harder tests for AIs.