Hmm. This is a very interesting topic and politicians should probably discuss this in the near future. The waters are already muddy and precedent is being set without any discussion. This is a complex issue and a simple answer yes or no is unlikely.
Here's my suggestion. Extend freedom of speech to cover any website or online service when they have a monopoly within in its market and there's no viable alternative to it. When they're that big, they're almost a utility. They have too much control and influence, that they shouldn't be left unregulated in regards to freedom of speech. If they become ideologically driven, they can influence culture and censor their opposition. That would be as bad as if that happened with the news. I'm basically saying they couldn't ban, hide users from other people or censor anyone unless they promote or incite violence.
1. For the ones saying that companies are privately owned and can deny service to whoever they want, that's false. That line has been crossed already. Companies can't discriminate. Might as well extend that to cover words.
https://aclu-co.org/court-rules-bakery-illegally-discriminated-against-gay-couple/
2. We already regulate industries that are so big that they can affect everything like phone, power, water, oil, food, medicine, etc. More importantly, ISPs (which people want more regulation for) are already regulated. Might as well start protecting freedom of speech on the big social media while we can.
3. The EU is already trying to impose regulations on social media in regards to "hate speech". Hate speech is anything that's offensive to the ones who have control of the culture. Remember me saying something about being ideologically driven.... http://money.cnn.com/2017/09/28/technology/hate-speech-facebook-twitter-europe/index.html
4. In the US, offensive speech is protected along with the other kinds. Because of that, the US should be the ones setting the global standard on this and not the EU.