They already implement a code of conduct to restrict behavior in their community.
The person in question is free to use the code and be an asshole. Everybody else is free to call him out for it.
With that said this sort of thing can result in mass contributor exoduses. One might prefer an in-between license like a per-file copyleft as you see in the Mozilla Public License, which is still GPL-compatible but does not put the full onus of the GPL on the software, solving this problem in a more narrow way (connectFree has to keep their proprietary software separate from ziglang when combining the two together, which forces them to be much more transparent about their value-add—things which they cannot keep separate need to be contributed back upstream).
Our terms matter. And considering this conversation is really about what it means to be OSS and what the tradeoffs are, we need to "get into semantics on what open source means". Too many people co-opt the term and we need to defend it.
For instance, there's Debian's[0] (which was considered authoritative enough that the OSI basically used it as their own) which spells out the freedoms necessary for software to be considered Open Source. This extends beyond the source being available to not discriminating against people groups, allowing for modification, etc.
There's another from the FSF/GNU projects[1] which lay out the Four Essential Freedoms. These extend beyond source availability to the ability to run the program as you wish, to study the program and to redistribute it (among others).
To say source availability == Open Source is to rewrite history. It's about user freedom and always has been.
Grey is a color somewhere between white and black. Water is the liquid that we drink, wash our dishes and cars with, the stuff that sits in the world's oceans, &c. "Grey water", however, is not supposed to be applied to anything that contains fecal matter, whether or not you can argue that it is both grey and water. There are such things as specialization and context. They're pretty important to the way language works.
I'm genuinely sympathetic, in that it rubs me a little bit the wrong way to say that one organization can define "open source". In practice, however, the only people I've ever seen actually arguing this are people trying to pretend that their license is open source when it really isn't.