You're doing a bit of finest "whataboutery" which is distracting from the reality, until they discover someone who is a member of a proscribed left/far left org, you can't judge the balance.Again, see my wider point.
We've seen a ballet dancer boycotted because she expressed right-wing views. There have been recent articles which have talked about how mentioning in theatrical circles that you're a Conservative is career-limiting. Look at the abuse the Lawrence Fox has endured for, frankly, saying what a majority of people think.
I'm not condoning right-wing extremism. I am though making a point that it all seems a little unbalanced.