Not even Brendan's worst enemies have ever accused him of being a moron.
Brendan was a leading figure at Mozilla since the very beginning of the project. Everyone very well knew who he was.
I didn't agree with all of Brendan's decisions. For example I think we should have prioritized process separation higher than we did, and Brendan was partly responsible for deprioritizing that, which I viewed as a serious mistake. But Brendan made a lot more good decisions than bad ones and from that point of view, everyone I know was confident in him as CEO.
Engineers certainly weren't looking for an "excuse to get rid of him". I assume executives and the board weren't either, or they wouldn't have made him CEO just before the controversy exploded.
Quantum (or part of it; much good work done in C++ code too) is based on Rust and Servo, projects for which I was sole executive sponsor from 2010 onward: https://news.ycombinator.com/item?id=12224047.
It's fair to say Rust and Servo would not exist as such if I hadn't been at Mozilla.
I'm among the actual founders of mozilla.org, we started working on it in fall 1997. Earliest wayback snapshot: https://web.archive.org/web/19981202152141/http://www.mozill...
Eich was kinda a moron and I don't think they realized that after he was onboard. IIRC, he saw no reason to move forward with the Firefox Quantum support and generally had some other bad software decisions.
I suspect the anti-gay stuff was more to justify a way to get rid of him and score some points in the process.