I don't know if it was marked that way by Noveske or if the PO had it done, but always found it amusing. I'd have done taxed instead of banned for technical reasons.
I don't think I'd want the attention that it might draw.
And if you are being hassled by an ATF officer, how will you prove him wrong? Think he's actually gonna let you fire it? What if you aren't even at a range?
Once a machine gun receiver...always a machine gun receiver. You will never modify the "machine gun" out of it. A machine gun receiver is defined by function, not looks. Same with semi-auto receivers. Mark it how you like, if it was manufactured as semi-auto...it is a semi-auto.