Whether something like that is considered abusive can vary from RP to RP. We personally consider it ok so long as it does not break with the CS on our characters or our plans for them. Benign things like simple answers/reactions generally cannot do any real harm.

We're not 100% sure, but we do get a feeling that problems with such use are more common in the less intricate RPs like Free & Casual than with Advanced. But then, character sheets are generally shorter in those, so the other players know less about what makes a character tick than the owner does. Especially when compared to advanced RPs like the ones we're in.

Still, the safest thing to avoid unpleasantry for this is to have it cleared up for everyone early on, maybe even have it as a clause in the RP's rules. There's few things as annoying as having an RP stuck because it requires the input from a single person, and that one is unavailable.