I'd say it's a downside because people can be fired with flimsy evidence or without being charged with any wrong doing. In this case, it appears from the principal's own statement that these teachers messed up. But in other cases, it's not so good. For example, students can lie and accuse teachers of misconduct - and the teacher can be fired with no redress. In that case, it's bad.
I see it as mostly a good thing. Yes, abuse can happen but there is also the point that it is easier to get rid of 'bad' workers without the unions insisting that they be given unlimited '2nd chances' and make firing just about impossible or too expensive.