As much as I’m automatically inclined to side with science over mysticism, there are other telescopes being built right now (ELT, GMT) in the same class, both in Chile, where the mountains aren’t sacred, but just mountains.
So - while they’re pushing on for now, it seems there’s as much dogma (we must have this telescope here) amongst scientists as their is amongst the spiritualists - yes, the top of Hawaii is a uniquely good spot for a telescope - within US borders - there are other spots just as good, however, but those would require international negotiation and cooperation rather than just domestic negotiation and cooperation.
It all comes down to cost/benefit, and I think it’s getting marginal for the TMT. They’re going to need round the clock security, as the protests won’t stop once it’s built.
It’s not too late to build it elsewhere - even in space. Launch costs have dropped dramatically since the TMT was conceived, and are continuing to do so. Assembly will then be the tricky part, as with JWST.