Yep, rather it can be made back to a pistol after that is a question for the NFA gurus around here. My question is why have the bulk of a 16" rifle with the reduced velocity of an 11"?
The important part is that you have the "muzzle device" permanently attached prior to placing a rifle stock on it. You can later take the stock off, and reconfigure it back into a pistol, but you would have one awkward pistol with that long flash hider on the end.
If it were me, I wouldn't mess up that Enforcer by permattaching a long flash hider, I'd pick up a beater carbine to use instead.