I'm not sure about the veracity of your claims of bias pre-Musk (I have heard of the NY Post story issue, as far as I'm aware they suppressed it on advice from law enforcement that it was foreign propaganda, which was later withdrawn and the block removed).

However in answer to this question:

> Did X suppress support of the other side?

If you have 2 options and you promote one artificially then that is the same as suppressing the other option, in either case you're making sure more people see one option than the other.