"Didn't Koda also start out as just a fan? I have trouble believing he was contacted by Bo"
Err, you kinda made my point for me here. Koda joined by going and contacting Bo and asking if he could help, so what's stopping everyone else? I mentioned my helping him not to brag (if I was bragging I'd have mentioned something that was actually impressive, this is not) but to point out that all anyone here has to do is get in contact and ask what they can help with.
It's not just a question of competence (well, it sorta is, but it's not the point I'm making right now), but of willingness. Anyone who tries to replace or significantly assist Bo won't get to enjoy the game anymore because it's really hard to get off to your own work. That's why people make fan games and don't get involved with the actual game. At the end of the day, if you removed Koda you'd just be back to the way things were before. It's not like Koda's involvement stops everyone else from helping.
[Obligatory disclaimer I don't think that Koda is great and that all is well]
I don't see how I've made your point given that when Koda joined there was no co-developer, but now as long as Koda is still in that seat is taken...
If what you're doubting exactly is why don't
we specifically step up and get in contact with Bo so that he lays Koda off and makes us his replacement, then I personally would tell you that I don't have the skillset necessary nor do I plan on acquiring it any time soon. But being on my same boat obviously doesn't disqualify anyone from saying that Koda should be replaced.
If what you're doubting is why no one from the Discord has done it, then there's a couple of reasons: Cordiality is one of them, it's pretty terrible manners to ask for someone else's job before they're laid off, and even if most of us here at F95 wouldn't give two fucks about hurting Koda's feelings, the Discord people have a much better relationship with him, probably because they interact with him on the daily. I still think they shouldn't like the guy one bit with how many fast ones he's pulled on them at this point, but I'm not an expert on psychology either so I don't know why they choose to keep up with that.
Another reason could be that since his position isn't vacant yet, there's no sense of urgency to lend Bo a helping hand with ToT. They're a lot less pessimistic over at the Discord so they don't make too much of the recent developments, but I'm positive there's a very good chance someone would jump in to replace Koda if he had been dropped from ToT beforehand. Ultimately the one responsible for making changes that facilitate ToT's development is Bo Wei.
EDIT: Also the whole thing about "you can't get off to things you created yourself" is completely subjective and in my experience, false. I don't know where you got that from, but if it's what's stopping you from trying to replace Koda since you say you also don't like him, then don't worry buddy, I'm sure you'll be able to fap to a ToT you contributed to along with the rest of us, unless there's something I'm missing.