Has Mozilla showed any reason to bet on them in the last decade? It seems like leadership is happy to sink the company and take bonuses paid for by donations along the way.
I'd rather see a new player in the space. I have no confidence in Mozilla.
If a 501(c)(3) non-profit receives a donation for a specific project, by law they cannot direct the funds toward anything else unless the donor releases the funds for another purpose. This is more of a thing with large donations than, say, a recurring $10/month. If a small-dollar donor tried to restrict their funding, the non-profit would probably ignore the restriction because the donor has no leverage to find out if their instructions were followed.
If anyone with a ton of money wants to focus Mozilla specifically on Gecko, Rust, whatever, then that person can probably get them to do it.