Only 30 days is way too low, people go on vacations lasting longer than that. It's a clear money grab IMO.
Exchanges' usually give a month to withdraw delisted asset, no?
You have a point about long vacations, but I don't think it's Bittrex's problem (or any exchange in general). We shouldn't store our crypto on exchanges, it was repeatedly mentioned here and there because it's risky, anything can happen. Not taking any side, just my honest opinion.
Other exchange like Poloniex don't do a recovery after the withdrawal deadline of a coin/token. If a user think it's unreasonable that Bittrex ask a recovery fee (or because of the amount), then just consider that they don't do a recovery and take it as a lesson.