I don't have the issue at my finger tips either. But what I recall is that they were talking about Asgardians not being immortal in the same sense as Olympians. I don't recall them articulating what that means.
However, both The Prose Edda and Marvel's stories indicate that the Asgardians rely on Idun's Apples to maintain their youth and vigor. There didn't seem to be a similar constraint on the Olympians in ancient myth.
EXCEPT: Marvel established that The Olympians rely on The Flame of Prometheus burning in Olympus for their immortality (that's actually critical to the plot of Avengers 50). So, although UOHOTMU overlooked it, the Olympians are no more immortal than the Asgardians. They just have a different means of sustenance.
Taking it out of the comics, I'd say there's another test to level. If they prayed to you, and built temples to you, and sacrificed animals to you, you were considered a god. All of that happened for the Asgardians. It didn't happen for any of the demi-gods, except for Dionysus, who was basically promoted to godhood, and allowed a seat in Olympus.