Generally NIMBYism involves push-back on policies that increase housing density to help more (and generally poorer) people live somewhere. AirBNB without regulation (and enforcement) doesn't help more people live in an area - in fact it removes long term residences from the market in favor of generating more revenue for existing property owners. Reducing the long term housing supply increases demand and prices, thus keeping poorer folks out.

Personally I don't mind AirBNB if it's only people renting out rooms in their residences. For instance here in Portland the law requires this. But it's poorly enforced.