Because you haven't solved the problem for FLOSS, you've solved the problem for non-FLOSS that might also happen to also be FLOSS aka contribute somehow to a FLOSS version of the project - but the solution doesn't help those under the FLOSS licence, and complicates incentives to contribute to FLOSS/"community" versions.
Great for corporates who can buy the support contract, but is also suspiciously similar to the "freemium" model were FLOSS devs are suddenly incentivised to make the FLOSS offering insecure in comparison to the paid licence.
In this case, Marak is his own bad-actor/saboteur, how would the support contract help? It would be far more likely to make free-users 2nd class users, and as such it might be better to simply keep the products managerially separate due to that conflict of interest.
And lets be honest here - when does something stop being a reasonable "maintenance fee", and start to become rent-seeking / extortion? I think if you want to get paid, you simply don't work with MIT/GPL, or fork to a different licence; Changing your mind halfway through isn't reasonable IMHO.
MIT basically means "anyone working on this codebase agrees to MIT terms for their code, and as such authorship isn't so important". If you change your mind, you broke your agreement. If suddenly your authorship matters, what about every other author who stuck to their MIT agreement?