Let's be clear here, it's not that they don't want content on their platform: it's that content blatantly violates their rules.
Encouraging the harassment of families of school shooting victims is pretty heinous, and not something I'd want affiliated with my brand. I also wouldn't want my brand to become a platform for someone who perpetuates conspiracy theories that cause true believes to pick up weapons and become terrorists, simply because that's how he makes a buck.
After all, both Google and Twitter have spent close to a decade silencing religious extremists on their platforms. Where were the free speech advocates when fundamentalist Muslims were silenced on Twitter and couldn't use the platform to spread their message?
Yeah, I equated the two concepts: they created rules to specify what they do and don't want on their platform. Sorry if it came across as them deciding arbitrarily on the fly.