I agree, mostly.
I don't think they should sue on the basis of speculative profiling. I think they should sue on the merits: that they were not breaking any law nor suspected of breaking any law, but despite this were unlawfully detained (however briefly) and assaulted. They shouldn't have reacted physically the way that they did, and I'm sure they'd admit that, but when you KNOW you are RIGHT and that you have done NO WRONG I think that's a very natural reaction. They felt threatened and intimidated and were, quite literally, cornered.
I think the guy in the news report pretty much nailed it. These two cops thought they could bully around a couple of "kids" and it turns out these kids actually know their rights and wouldn't be pushed around. You don't have to be a minority for that to happen - to be bullied, that is.
The cops should get a massive suspension at least. I don't know if they should necessarily lose their badges over this. Glad I don't have to decide that. I think the charges should be dropped though. If the cops knew in their hearts and minds they were 100% in the legal clear, why did the physicality settle down before we see anyone in handcuffs? Why did they apparently relent to some degree?
edit: just to clarify I wouldn't let these two cops skate by any means. In the context of the police abuse we're seeing across the country, I'd say in a heartbeat to fire them. But, to be fair, we don't know what kind of cops these two are aside from this incident. They made an enormous mistake and should be reprimanded. I'm not going to pretend to know 100% that these two are the worst kind. We simply don't know that. The locals do. Let THEM decide and not the DPD who surely will protect the most corrupt.