I don't really know the specifics of how this works but the story is that he wasn't jamming the police comms, he was trying to "skim" the information like frequencies from police devices so rioters could eavesdrop on police communications and better coordinate the evening's festivities.
I don't think the police took Gugin's cell phone so any evidentiary value there is long gone. The police likely didn't know he was trying to do something like skimming.
You can't say he was "clearly non-threatening". He is a known instigator. was refusing to follow directions, approaching police, acting very suspiciously, all during a riot. Not a lot there adds up to "clearly non-threatening". The push does not seem too extreme either. I suspect Gugin, as an experienced agitator, got the push he wanted and took a dive. Perhaps he misjudged and smacked his head harder than he anticipated but even that seems weird to me. Do you know how frigging hard you have to smack your noodle to actually cause blood to come out of the ears? ANd once Gugin hits the ground, he gets all comfortable, crossing his legs. I've seen people get knocked out (you can see it on recent riot video if you want), they go down and stop moving, they don't get comfortable once down.
I dunno man, it all just looks weird as hell. I'm not sure what I see on that video.