Bill Nye is a a fool for letting his politics pollute his scientific reasoning. But a mechanical engineer has as much or more “science” education as other professionals who call themselves scientists.
Of course. More significantly, a BS in mechanical engineering implies more knowledge of hard scientific analysis than a PhD in "environmental science" does.
But when Bill Nye says he's a "scientist" he means he's a hifalutin' theoretician like his climate science PhD pals.