My reading of the situation is that Twitter etc. we're fine turning a (not very) blind eye until President Trump did something that is arguably illegal. At that point self-interest kicked in as they realized "oh crap since he did this with the help of our platform and we've been letting him violate our own rules we may have legal liability OMG ban!"
Heck, AWS hosts the National Enquirer, the publication that tried to blackmail AWS's owner with genital pics. It's difficult to claim anti-conservative bias when so much borderline and over the line extreme right content is allowed to remain.
If there's an appearance of conservative bias then I believe it is because between President Trump peddling conspiracy theories and general hatred of those who oppose him, it simply caused more extremist content to be posted, and therefore more to be banned. It's not bias is there really is a lot more extreme right content.
