...when the police are still harassing them, carding them, and shooting them.
Also, when the police are still raiding gay spaces (as in Project Marie linked in my post) including bars on Church Street, and writing citations for things like public intoxication during Pride, or even closing them down (as has happened during multiple previous Prides when I worked on Church Street in a clothing shop), it's difficult for the community to trust the police.
There was a recent story of a black teenager who had been robbed during the day near a major intersection in Toronto. He called the police, and they searched his bag, cuffed him, and asked him about his activities before taking his statement. I agree, there should be outreach between the police and the queer community and the black community, but there are fundamental problems in the police services that need to be addressed. When the SIU decides not to pursue any charges against the officer who shot and killed Jermaine Carby, who was a passenger in a vehicle involved in a traffic stop that the officer decided he wanted to card, then it's hard for the black community to trust the police or the process.
Also, once again, the police are not in any way banned from marching, but they may not march in uniform or armed.