I think shooting someone trying to attack you with a hoe generally counts as self-defense, but I don't understand why
“The use of a Taser in this situation with the amount of time or the use of pepper-spray would not have been something we would have been able to react to quick enough. Ultimately we have to stop this problem … law enforcement officers are not required to be hit over the head with something. What happens when they get incapacitated? … The deputies followed through with what their training protocols are.”
This seems like exactly the situation tasers are meant for. Even if attempting to use a taser would have been riskier for the deputies, IMO accepting a reasonable amount of risk is part of their job. "Take the risk of confronting an aggressive teenager, but not the further risk of attempting to subdue him non-lethally" isn't where I would have the line drawn.