It is disingenuous of the police to claim that they were 'raising awareness' - ie informing Margaret that her blog was being interpreted as 'hate'.
In reality, there will be an Incident Report and the officer will write something along the lines of: "Contacted the writer and warned her about her future conduct". Margaret's details will be recorded. In the event of a second complaint, the police will cross-reference with the Incident Report and ESCALATE police action.
I would advise anyone who receives a phone-call from the police about a non-crime hate incident to END THE CALL as soon as the officer explains that they are following up a complaint about a hate crime.
You may be tempted to hear the officer out. You may be tempted to get into a conversation. You may be tempted to justify what you've written/said. The more you talk and listen and engage, the more easily that the police can 'write off' the incident by saying that you have accepted a warning. If you put down the phone as soon as they've outlined the complaint, the police officer is stumped.
They had hoped to finalise the incident with a quick phonecall and a short write-up on the incident report. If you end the call, the police will have to try something else - like a letter or a request for an interview - which is all very time-consuming and a waste of police time in comparison with a quick phonecall.
Your only words should be to ask for the officers name, number and station - for the purposes of making a complaint.