Indeed. Spam filters, porn filters, swearword filters... all of those have precedents (in mainstream, non-social/internet media) and are perfectly acceptable by most of society.
In addition, notice that even GMail doesn't actually filter spam. It just hides it - it's an assistant, not arbiter of what you should see. It's more than happy for you to adjust the filters (for yourself personally).
Edit: GMail also does prioritization as of recently - but again, the purpose of that is to help users not filter content. Again, those algorithms are also adjustable for each user separately, they just have some "smart" defaults.
In addition, notice that even GMail doesn't actually filter spam. It just hides it - it's an assistant, not arbiter of what you should see. It's more than happy for you to adjust the filters (for yourself personally).
Edit: GMail also does prioritization as of recently - but again, the purpose of that is to help users not filter content. Again, those algorithms are also adjustable for each user separately, they just have some "smart" defaults.