is it OK to threaten to Taser someone already handcuffed?

Atlanta Journal Constitution (Rhonda Cook):

A Fulton County deputy has been fired for using her Taser on a handcuffed inmate and then lying about it to internal investigators, according to a report filed Thursday with a federal judge who demanded an accounting of the January incident.

I was with a citizen registering concerns about the Forest Park PD using inappropriate, if not excessive force, during an arrest. Sgt. Eric Bell, the Taser training guy for he FPPD, said that it was OK to threaten to Taser a handcuffed subject even if it wasn't OK to follow through.

IANAL (I am not a lawyer), but if using the force is illegal it's a battery. And threatening a battery is assault.

So, I think it's highly dubious for cops to be threatening to Taser subjects already restrained by handcuffs. And I am concerned that the head training guy is saying this is OK. But I was already suspicious of the Forest Park PD being a overzealous in the use of Tasers.

BTW, Amy Rita's claims about Tasers in the Forest Park Post don't make sense.