Yes, they were publicising their disagreement with the teaching of the Catholic Church. How were the police to know what they would do next?
The world's media would have put any disruption of a Papal Mass on the front page; you know that as well as I do, you know the value of publicity and their sole aim was to gain publicity? 
You agree with them, with their aims and would perhaps approve of such a demonstration, that is your right. It is also the right of the Roman Police and the Vatican Gendarmerie to nip such a demonstration in the bud. That is the issue here, not whether 'ordaining' women is right or wrong.