By the same argument, Google could exclude a political candidate from their search results entirely, or bolster a fabricated news story claiming the candidate was a child-molsting satanist to the top of their results. Would you also consider that acceptable?

These companies have become, for many, infrastructural. For these companies (who also sell advertising) to take these kinds of actions would essentially be them bypassing campaign finance rules to give MASSIVE contributions of free advertising to candidates. I think its fair to argue that that would be unacceptable interference.