The fact that Glenn did so poorly in the primaries doesn't help his general election argument. He probably would've done even worse than Mondale did, maybe even lost all 50 states.
I'm not sure if he would do quite that bad, but yes I don't see how he dramatically improves the map for Democrats. Minnesota probably goes Republican under this scenario and Ohio is too much of a swing state for me to see the Homeboy Advantage
TM being very effective when the national environment favored Reagan as much as it did ("Morning in America" worked so well for a reason).
But really, the main point here is that John Glenn was just BORING as a candidate. I mean the guy was an ASTRONAUT, not an actor. His life's dream was to go to the stars, not giving wit laden speeches and being in picture perfect pose whenever the cameras were around. Amusingly enough, NASA psychologists determined in the early 60's that Glenn, as stiff as his speaking style was, would be the astronaut best suited for public life. He made his first Primary attempt in 1964 when he resigned to run against the incumbent before he slipped on his bathroom floor or some sh*t and hit his head on the bathtub and suffered a concussion. When he again ran in 1970 he was defeated in that primary by
Howard freakin' Metzenbaum, who he would face four years later in 1974 after the man was appointed by the incumbent Governor to fill a vacancy.
It was only when Metzenbaum provided Glenn a massive opening to attack him as an unpatriotic SOB that Glenn was able to destroy him. And even in his "moment" Glenn is too calm and too stiff.
Mondale was at least capable of being excitable occasionally.
I mean, that is not to say that Glenn couldn't motivate people, he most certainly could. He seems like he's the kind of guy you could have a drink with and that probably helped him a lot in Ohio. However nationally, I don't see it helping that much against Reagan, who was both a drinking man's president and a made for tv one.