Quite the opposite
Sorry, I missed the "Joseph Dunphy's response" part. But it does little to refute this anyway, as the phenomenon has been noticed not just by Salem or Patterson but by others as well (e.g. Mary Midgley). He points (quite correctly) that most engineers are not extremists or creationists, but since most educated people in the world are not extremists or creationists this seems not very relevant.
From what I know about this to date, I take that among people with higher education engineers indeed are overrepresented in creationism. I will however happily stand corrected if pointed to new evidence.