What is even the grounds for this? You can't call election interference on a private company because of a preference for a candidate. That's like if Harris wanted to sue Fox News for a bias towards Trump. Private companies are allowed to have biases.

It is also completely possible that the supposed preferential treatment may be due to public opinion and news reporting. Kinda like how if you lie a lot, people call you out on it, but that doesn't make it illegal that they don't call out your opponent equally as much.