Vote? By the same people who created this mess in the first place?

It's a sure was to demotivate a serious complainer. He knows the vote will be turned against him.

The only was to give him confidence is to promise that the plan will be judged objectively, not democratically.

Well, that's part of politics. To get people on board the complainer will then have to try to build some consensus. If you start out from the premise that the vote would be turned against him then he should simply leave for a company that is worthy of his talents instead.

Objectivity in tech is more often than not in the eye of the beholder.