Sure, I think it's totally fine to be appalled by deplatforming. I do think people should have a voice, I also think it's the right of platform owners to decide what terms of service they set and what discourse they consider ok. The point is not to say deplatforming should be ok in all and any cases, the point is to highlight the hypocrisy, or perhaps abandonment of so-called core/staunchly held beliefs, that emerges once those beliefs are suddenly at odds with maintaining power.

edit: to put it another way, it unveils that one of the identifying principles of the ideology is not a principle but a convention, upheld so long as its convenient.