"Illegal" is probably the wrong word to use here, since the iron ring is not governed by any municipal, provincial, or federal law.
I have a B.Sc. EE and yet work mostly in web/mobile software. I don't consider or present myself as a "practicing engineer" but I still wear the ring as a reminder of the obligation I have towards anything I create for other people to use. I probably wouldn't give it to my girlfriend to wear, but to each their own.