I was responding to the question about what link OP was trying to draw between BitChute and Mastodon, no idea at all about the second question re censoring Mastodon links on Twitter.
But again, responding to your parallel comment, OP is not saying that BitChute is a competitor to Twitter. It's that entrenched player <a> is (soft) censoring new competitor <b> where <a>, <b> are filled in with (Google/YT, BitChute) and (Twitter, Mastodon).