Sure, the issue is that every time a political partisan or politically partisan organization gets banned from a service, they and their followers will always believe it's because of the party they're a member of, and not because they were being an asshole. It acts as cover to engage in any kind of behavior at all, as long as you're a partisan. That isn't what those protections were meant for.
Rules are enforced by imperfect detectors of infractions because there is no such thing as a perfect detector. No matter how careful a review process is, failures will always happen. Innocent people are convicted by real courts through decades of appeals in spite of all the due process. You will always be able to find some instances where a member of party A does exactly the same thing as a member of party B, but only one of them gets punished. Does this mean we should try the best we can and accept that we will fail a non-zero number of times, or should we never have rules instead because that's the only possible way to be fair?
I'm going to be perfectly honest here. I don't follow Twitter at all. I've never had an account. I haven't read an article from the NY Post that I can remember in probably 20 years. I don't actually care about this stuff and think it's silly internet drama that should not be dominating national headlines. So it's entirely possible Twitter really was biased here. I don't know. Organizations are not never in the wrong. When black people were banned from every lunch counter in 15 states, it wasn't an innocent mistake by organizations trying their best to exercise their right to freedom of association. When communists were purged from Hollywood, they were definitely targeted because of their party, not because they'd explicitly done anything.
But without stooping to the specifics of whether one single incident was right or wrong, I would like to agree that it is okay for a service like Twitter to have terms of service and remove content and block accounts that breech those terms. Legally, at least right now, they are not treated as a common carrier, but if that ever changes, one of those terms of service can't be "no Republicans," but that also doesn't mean no Republicans can ever be banned. If you think you can prove disparate impact in a court of law, have at it, but just be aware that you're in the ample company of every political partisan ever who believed themselves to be some unjustly persecuted minority being suppressed for just telling the truth. The fact that some small number really were doesn't do much to impact the overall probability distribution of holding that belief.