It's only justifiable if there was no other way. Given that Yuta was sent reeling by the previous blast and only barely managed to get up, hit her with another one, a sustained blast, and she'd be sent sprawling. In any case, I can't believe that one setting will send her stumbling and the next setting up would vaporize her. There will be SOME setting that will knock her out.
And as for her punishment, well, put her on a planet with no way off, and she won't be much of a threat. We saw in classic Trek that there are any number of prison worlds that make sure that prisoners have no access to the supply ships.