As others have said, there are no rights being eroded by him having his account terminated by a private mailing list company.
Whatever you want to think about him, the content he produces does promote white nationalist ideas, as well as other negative alt-right and anti-SJW views. Whether he genuinely believes what he says or just does it for views is irrelevant, his dog whistles contribute to the radicalization of his viewers, often young white males. He is a stepping stone for viewers to other even more radical ideas, like "the great replacement" and "the Jewish problem". Engaging with him just gives him credibility, which he does not deserve.