Legally, it seems self-evident that YouTube should be permitted to curate their own content however they deem fit, whether it is fair in the abstract or not. I wouldn't want to live in a world where anyone was compelled to publish, disseminate or engage with content against their will.
Morally, this sort of mass banning of a position ought to be a taboo if we want a free society. We, as free citizens, have every right to petition that an open stance be adopted even if YouTube is well within their rights to refuse.
The other thing I tend to think important is to always ask one more question - would I support this action if it was taken if the sides of the issue were reversed? Sometimes the answer is 'yes', but I've found it a warning sign when the mental response is 'but....'