I think we may have a misunderstanding here. I am not ready to say this guy was wrong to use his taser. I'm also not ready to say he was right. I don't know enough yet.
Just sitting there looking spacey and not following orders would be enough to get my pulse going, but I'd still like to see some agression, or at least LONG period of non-compliance. Was there backup there? Who knows the ethos of his dept. or the siutation in general, but I think my first thought would be to radio Dispatch and report a non-compliant, non-responsive citizen in one of the vehicles and ask for backup.
From what I saw, there was the taser cop on the passenger side and (I think) two others on the drivers side. There were two paramedics there too. The whole thing is on the dash cam. The paramedics and drivers side cops didn't look too worked up. Taser cop just looked ticked off because he was being ignored.