Not the point. First, just because it isn't classified doesn't mean it doesn't have to be protected. Secondly, he had easy access to SIPRNET, so reporting sensitive information via it would have made a lot more sense. Thirdly, his immediate boss, Commander Carrier Strike Group NINE RADM Stuart “Studa” Baker was literally just down the hall from him. I understand there reportedly were "tensions" between Crozier and Baker, but that's no reason to jump the chain of command except for extreme circumstances.
Again, there's too many unknowns at the moment to determine who was actually right; and to be honest I suspect all parties have blood on their hands when it comes to this incident; but there is clear evidence that Crozier had better mechanisms to communicate his concerns, and didn't use them. Does that justify his firing? Not really, but it does address the accusation of claims of bad judgment in terms of communicating.
https://www.washingtonexaminer.com/opinion/dont-fixate-on-secretary-modly-we-need-to-hear-from-rear-admiral-stu-baker-on-captain-crozier