Mandating "correct" pronoun usage is separate from the technical and business reasons why twitter isn't an open standard/protocol like email or IRC. Jack Dorsey absolutely had the authority to mandate twitter be an open platform, but then his company would have been less attractive to VC firms and may never have gone public. He wanted to maximize his chances of a big payout, so that's the choice he made. That's not a "capitalism" problem; that's a "Jack Dorsey" problem.