Perhaps, but I don't see that as an issue. The 51 year old grandma could just as easily have been a 60 year old grandpa, and not much bigger or stronger than granny.
The real problem was procedures that are standard in other courthouses and jails that were not followed here. The person actually in contact with the prisoner is not to be armed (she may not have been, I heard an interview this morning which said her gun was locked in a "lock box" where the deputies put their firearms when handling prisoners, but after he overpowered her, he of course got the key). The unarmed "handler" generally has an armed backup, or more than one, who stay outside the reach of the prisoner. Best procedure would have been to have granny be the backup, and have deputy Big Bubba be the "handler", but the other way around probably would have been OK as well.
And the full story, now that I've read it, confirms this
Proper procedure would have put the suspect alone in a locked cell before his handcuffs were removed. He then would have been allowed to change clothes, and the handcuffs secured again before the cell was unlocked.