what bothers me the most is here is an ambigious shortening of a phrase "professional enginner" (or P.Eng.) which I would be fine to say, yes, dont call yourself a P.Eng. when that is part of a cult/guild/group/ect; but then it is also restricted is the "generalized" term of it. all of the other points folks write about actually add-more-details, but in this case they're restricting the detail-removed form; bummer for them and I hope that "confusion" (enforced by the "Association of Professional Engineers and Geoscientists", (maybe we should abbreviate them as "Ass. of PEG") ) is one day better handeled and not restricting a general term

edit: can you call yourself an engineer but not part of ass of peg in the same sentence/paragraph?