Is it respectful? This new version is certainly not what I put money to support, and if there was any indication this is what it would become then I wouldn't have given anything. I have given advice and feedback as the dev cycle went along, but it was ignored.
This might be respectful if it was free, but certainly not as-is, and definitely not with the responses the dev has been putting out.
This is the exact definition of investment.
You pay for a game that is currently incomplete and for what you feel like will have a great potential, a bright future.
Sometimes you get disapointed, sometimes you don't.
You've paid him to show an extra support to his work, it is your right to cancel it.
On the other hand, while I agree it definitely was a risky move to shake the playerbase by doing what the dev did, it is their right to do so, and whether you did or did not pay him for that so-called uturn, shouldn't impact the respect.
Keep in mind that I'm writing this post without having any knowledge about possible questionning the dev may or may not have proposed to consult their donators. And should the dev decide to follow this path, over yours (and many others), implies that they at least got support from quite some donors, I assume ?
Point being, things (the game, the com, the decisions, mainly) could have obviously been performed differently to get better results, that's a certainty, but so could have been some of the answers in this thread.