reading through that, they were within their rights. part of the definitiobn as to the ruling was that the police were in pursuit of the suspect. basically, you can't turn round and run into your house and go "nya nya you can't arrest me".
further, it was a 911 call which means the police are ALSO required to think on their feet and act according to the situation. Given that the defendant in this case was in a seemingly agitated and abusive state, for the safety of all involved, the police were in the right to act as they did.