In this case, "I don't want another giant telescope on my culture's sacred mountain" isn't about astronomy at all, it's about the culture (and the larger perspective of indigenous interest in local resources, and respect for a pre-existing treaty that wasn't quite honored -- these folks aren't primitives or hippies, they know very well this is a political process in the real world).
That said, the idea that NIMBYs won't oppose a luxury hotel or housing development is laughable. My NextDoor is filled with people posting proposed development of our downtown, criticizing it with specious reasoning, and trying to rally people against it. The nature of the development doesn't matter. How much it will improve our property values doesn't matter. How much it will help with housing or traffic doesn't matter.
A luxury hotel... I can already hear them shrilly decrying how we don't "need to bring more people to the area," as stupid an argument as that would be for a hotel.
I don't know how to flesh it out better.
IIRC, the anti-TMT protestors would ideally like all the telescopes on Mauna Kea removed. However, obstructing the construction of the new one is the most practical present course of action for them.