There isn't anything mature about a 5" ewe, that's basically protecting lambs. If you look thru the harvest stats you will find 7"+ ewes with one growth ring. Lots of Ewes with a lifetime of reproduction in front of them get killed every year.
Its legal and I try not to judge what other people want to hunt, it just makes me a little sad inside with the amount of time, money and effort that goes into sheep conservation when you read the stats and see young and prime breeding age females being taken out of the herd.
Sure, winter or disease could get them also, and being in somebody's freezer is much better then that alternative but there is also the chance that Ewe could have put 6 more sheep on the mountain in her life.