Such a short length makes it still HANDY for use with the 9" OAL can. Snap on can-attachment means virtually nothing. shtf, can will nearly always STAY on the barrel. So the "wear" or the 10 seconds necessary to screw it off or on means nothing.
The snap on attachment means that you can carry the suppressor off and have the rifle balance normally. If you need it, it takes only a moment to install. If you don't have that moment then people are probably shooting at you and you're in deep doo-doo anyway.