Relays are just someone elses server and harddrive. Those "someone else" will have an opinion on what they want to store on there. There is no way in hell that all relays will accept anything from anyone. You just need to find the relays you agree with or better yet host your own where you own your own speech.
Discussion
Having a way to filter out spam is good,
But if you end up targeting npubs due to some notes, and that is widely adopted...I fear this.