I assume this holster was not for a taser, which explains your hesitancy to draw and fire. Perhaps a taser is just a little too easy to use.
If I'm confronting some whack-job and I've got the authorization to use a taser in circumstances like these ... I don't know ... all kinds of bad things can happen quickly. Let me just say that, although there may have been other and better ways to handle this person (especially knowing what we know now), I can understand his use of the taser.
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.