I don't have any problem with Twitter adding a paid option. I've never even used Twitter nor will I ever so it so anything they do to the platform doesn't affect me. It just seems weird that people are making the claim that you can't monitize a large unpaid user-base.
You can, but you basically have to masquerade your company as a user-facing service while behind the scenes it's almost entirely just an ad and ad tech platform.
I think it's plausible Jack Dorsey maybe genuinely just didn't want to sign that deal with the devil. I know I wouldn't want to if I made Twitter. (I have no idea if that's what happened, of course. Maybe he wanted to but couldn't find a good way to achieve it.)