Part of the reason it was changed to say "remove" a stress was in an (apparently futile
effort to imply that his ability could be used even if no eyeballs were rolled.
Spending a stress token is not defined in the rules. (That is, "spend" isn't defined as a general operation you can perform; it's defined on specific kinds of tokens, but stress isn't one of them.) Removing a token to gain a benefit is definitely how it needs to appear on the card.
In conversation, though, it's pretty clear what spending stress means for Keyan.