If you could provide examples of this sort of usage in the utility theory literature or textbooks, I will gladly retract my corrections. I don't recall seeing "risk aversion" used this way before.

It is just the standard usage if applied appropriately to utility. Even the 'certainty effect' that you mention is an example of being risk adverse with respect to utility albeit one highly limited to a specific subset of cases - again when the object being risk is evaluated in terms of utility.

nyan_sandwich has edited their post to reflect that minimax was their intention.

Which may apply somewhere in the post but in the specific application in the context just wouldn't have made sense in the sentence.