@failures art,
I don't see how you can draw a reasoned conclusion on his motivation for being there.
As far as we know, he could have gone there with love in his heart and the intention of trying to save what he believed to be endangered souls.
Personally, I don't believe this, but that's due more to my innate cynicism than anything he says on the video. If you set aside the use of a loudspeaker to project his voice, he certainly wasn't acting in a way that I would consider rude...unlike the red headed simpleton and the couple of other people who respond with curses.
In any case, as you well know, whether he was being rude, or his motivation involved hatred for anyone is legally immaterial.
I'm not surprised that some in the crowd respond with antagonism to his street preaching, nor do I have a real problem with them doing so in a crude manner. Whether from love or hate, he is condemning their life-styles and there is no reason why he should not expect some sort of confrontation. I don't get the impression that he is really alarmed or offended by the response he received. He certainly didn't look to the police for intervention when his mike was being grabbed. So, he's not complaining.
Unless one subscribes to an absolute "live and let live" ethos there is bound to be some conduct, or expression of opinion that one would condemn. Whether one has the brass to do the condemnation in public and before a crowd of the people being condemned is another story.
Condemning members of the KKK is something I'm sure would be widely shared in, and those who did so while face to face with the Klansmen would probably be considered somewhat heroic by many of us. I would even venture to say that those condemning them would be expressing hatred for the Klan and it's members.
We don't hear many voices decrying condemnation of the KKK as "hate speech." I've seen some of that condemnation in person and I can assure you that (if facial expressions, tone of voice, and choice of words means anything) many voicing it were feeling real hatred.
Most of us are OK with this because we feel either that the KKK deserves hatred or that those who hate them are expressing righteous outrage.
Assuming the street preacher is expressing hatred, I wonder if you believe his thinking and motivation is drastically different from those who protest a KKK gathering?