I don't know how you kept your cool bro, I would have told him to mind his own the first time he offered his 'advice'. Probably thrown a couple of 45s at him too.
AAP, I gave you K for a great story. I get that shit all the time at my gym about how I should do things. I just agree with them and act like they know everything, then lift more weight than them on all the workouts they talk about.