I'm the maintainer of glitch-soc (a fork of Mastodon which I haven't started, but I have become the main developer of), but I also contribute to upstream Mastodon.
Because I don't have any personal issue with Eugen (even though I regularly disagree with him, on features, how Mastodon is handled, etc.), because it's still upstream and the most used version of the software, and because I plan to get paid for it.
I try to have all improvements both in glitch-soc and upstream, but some are not accepted upstream (e.g., bookmarks, hidden follower counts…)
I try my best to listen for feedback and hear from people Eugen isn't listening to or who don't want to engage with him anymore, but ultimately I'm not managing glitch-soc very differently (I'm more or less the only maintainer, things are mostly done through github, etc.) and it's probably easier on me because I have far fewer direct users.
For these last reasons, I'm interested in what Florence will achieve. I'm also planning on giving them a hand but I don't know to what extent yet.