mollie Crime is not limited to violence, though, is it?
Fraud for example. Are you saying that because fraud does not involve violence, or usually threaten the safety of people, police should not investigate it so that the courts can call fraudsters to account?
What about the Birmingham dentist who defrauded the NHS of over a million pounds? Was it a waste of police time to painstakingly investigate, make sure the evidence was watertight, and prosecute her?
As we have seen, you don't have to be a Twitter follower to become aware of the viciousness of some people's tweets. If the person posting them has the intent to incite hatred, or even if they don't, they should be called to account in just the same way as if they had plastered their thoughts on a billboard or published a pamphlet and stuck it through a door.
(In case you think that doesn't happen, it does. I once phoned the police after a highly offensive, anti-Semitic leaflet was put through my door)