I think this is how I feel. The basic crime is stealing or maybe vandalism, something like that.
I think it's fairly likely that it could be from someone who has some beef with the message of the Pride parade. That could mean a lot of things though, maybe weird religious people, or maybe a bunch of disaffected lesbians, or people who think too much funding is being given to events like this while there are potholes in the streets. I don't think it's a good idea to make too many assumptions about their reasoning off the cuff.
It could also potentially be kids pulling pranks or someone with another kind of beef with the event, like they don't like the litter left around after.
But even in the former case, "hate crime" seems a bit extreme. Maybe because I don't think it would necessarily be called that if the group was a differernt one, it would be more likely to be interpreted as a political protest that crossed the line a bit.
I'm not a big fan of hate crime laws anyway though, I'm not convinced the same crimes are worse just because the motivation is about a set of things on a list rather than something that doesn't appear on the list.