Interesting, though this sounds like it would really hamper the idea of the national popular vote compact which I'm personally pulling for. And really calls into question the whole electoral system if the electors cannot be constrained by their states at all. Just bribe or threaten 271 people and the whole presidency is yours really since states can't invalidate faithless votes...
> though this sounds like it would really hamper the idea of the national popular vote compact which I'm personally pulling for.
I'm a supporter of NPV. I don't think it's likely to be a problem, although this feels like something that will shake out a lot further in the federal courts.