"Competitor" LOLTwitter can do as it pleases. It may not be good for business or its shareholders though. My only real interest in this topic is the actions taken by Apple and Google to take out Twitter's upcoming competitor.
Nobody in the world outside a few far-right whackadoodle US conspiracy groups gives a sh!t about Parler.
"Political opposition" is not banned from Twitter.
Liars and bigots who incite unrest and violence are.
Learn the difference.
You can't do that sh!t in real life, why do you think it's okay to do it on the internet?