Does it matter? It didn't stop Trump from creating Truth.social, did it?
Why couldn't other right-wing influencers get together and do something similar? Perhaps because there never was actual censorship?
Perhaps they just attracted more suckers to support them by bitching and moaning about "censorship" and "deplatforming" than if they went on and actually took control of their own social media presence.
2) I don't think Mastodon was more than a rounding error before Musk bought Twitter.