If you have a huge firehose of opposing opinions, and you choose to censor 1% of the opinions of one side versus the other, you have effectively become a newspaper with an editorial board.
The only way to avoid this is to permit ALL content (which we have decided is untenable), or somehow precisely censor as much on one side as the other (which is impossible).
I don't see what "sides" have to do with this. You have a policy of what is acceptable content or not and apply it uniformly.
If one "side" is breaking rules about promoting violence, and the other is not, they are not being censored or repressed- they are just breaking rules and their content will be removed.
In the US we seem to feel its ingrained that there has to be two (and only two) binary "sides" in opposition to one another. This is the minority case around the world. Things get a lot thornier when you have a whole bunch of different sides that tend to be focused around a narrow view of issues.
The only way to avoid this is to permit ALL content (which we have decided is untenable), or somehow precisely censor as much on one side as the other (which is impossible).