There is a difference between censorship and the right to not have to listen to somebody. Being banned from having a platform to speak from could count as censorship (for example being banned from Reddit). However with Lemmy those on lemmygrad are free to say whatever they want, the difference is that everyone else is just as free to not have to listen. The idea of the Lemmy instances is that they have the ability to curate content - an instance catering to an LGBT community is not going to want to have to listen to right wing evangelicals and you join up on that knowledge. If you want to have the option to hear every single voice then join an instance with that mindset or just host your own.
The Brexit lies and their perpetrators are indelibly etched into my brain.