I mean, sure. It isn’t actually using concentration but they are activating an ongoing effect that removes their ability to concentrate which is what I imagine other martial “concentration” features would do unless we want to just give them actual spells (which I’m against for the most part). Sure it removes the ability to cast spells while it’s active, which might be too restrictive, but Martials should be using weapons instead of spells most of the time anyway.
I’ve only briefly played a barbarian above level 7 so I can’t speak to their play-feel but I’m all for buffing barbarians both in and out of rage.