It's technically peaceful in the same way that me raising my fist while staring you in the eyes is technically peaceful, although that's a very barbaric type of threat while this was a very civilized one.
Raising your fist clearly implies you are going to hit me if I don't agree. Here the police made it clear there was no crime committed and took no action when he said he wouldn't take it down.
You're telling me that if I called the police and told them someone was making fun of me on twitter, they'd visit that person's house and ask them to stop?
Which?
No, technically that would count as common assault which could get you arrested and charged or at least cautioned.
I don't see how the police did not act peacefully. He would have had the option as to whether to allow the police in or not, and I don't see how them asking questions about what he did is bullying.
The police did state several times that he had not committed a crime, and they were seeking information.