if crits get changed for hide and seek it opens up the can of worms that is 'disable all crits' that it will inevitably turn into if you let this be implemented and you'll get no end of it either here or in the discord until it gets changed back, so no matter the decision, crits will go back to being as they are now when this idea doesn't work
I believe OP is referring specifically to the 100% crits BLUs during the 90 seconds of hiding time REDs get, not to random crits or anything natural to TF2 (he can correct me if I'm wrong I suppose, but I assume he's referring to that since he discusses killing REDs in Armory). I don't think that anything proposed here could be used as reasoning for changing crits any further, such as removing random crits, because all that would be removed is the 100% crits BLUs get then, which is itself unnatural and not comparable to natural forms of obtaining crits in TF2.
There's no real con to removing the crits either besides I guess not being able to kill REDs who enter Armory as easily. Although, if I remember correctly, during that same time BLUs also have an Ubercharge effect, so there's no risk of them being ambushed, especially since REDs can't pick up ammo in the first place.