> However, if those maintainers find that their faithfulness is rewarded by being told that they don't actually maintain the project, they're just tending it while RMS is busy
Someone or some group/process has to be in charge, be the final decision-maker for a group. In the case of the GNU Project, the Free Software Foundation is likely that decision-maker as the owner of the trademark for "GNU". The FSF as a non-profit organization has articles of incorporation and bylaws [1] describing its process for making decisions - but it is a corporation, just like any corporation, and its decisions concerning its assets are binding in the same way as if Google made a decision about one of its products.
I haven't read the FSF bylaws in detail, but it sounds like RMS believes that he has decision-making authority over the FSF and GNU Project, which he probably does. Someone has to - what's the alternative? In organizations like the FSF and Wikipedia, someone or some process has to have the authority to make decisions. There is no way to delegate actual decision-making to the "community" at large. A person has to have it, either individually or as the executor of a process.
I suppose the alternative is having no trademark nor legal organization in charge of a project, but in that case, a disagreement could result in two different projects contending for the same name. Besides, someone or some organization ultimately has to be in control of properties such as domain names and source control accounts. The moment that a project manages any properties like this, there has to be a formal decision-making process or the project is at risk of chaos. The person who has legal control over project properties like the project domain name, or IP like its trademark, is in de facto final control over the project itself.
There are undoubtedly options for going over RMS's head, such as convincing the directors of the FSF [2] to take a vote on the issue, or take a vote to remove him as president or as a director. Alternatively, people who feel passionately about this issue could lobby the FSF directors to put pressure on RMS to reverse this decision or delegate it, without using the mechanics of a formal vote, such as by threatening resignation. Furthermore, donors of the FSF could threaten to pull their funding over the issue.
Alternatively, project maintainers can fork the codebase and carry on under a new name, managed by a new organization, which is their right to do since the code is open source and free software. To the extent that an open source project or any project is operating under a specific name, managed by a corporation, we should all understand that someone is always "in charge", though that person or group may act with a light touch or operate largely behind the scenes.
[1] https://www.fsf.org/about/financial
[2] https://www.fsf.org/about/people/board
P.S. This comment is not an endorsement of either side of the issue in a normative sense. It is intended to be a positive comment concerning the expectations we should have in working with corporations.