I never said he was always meant to be 70. It’s the opposite: I am sure he wasn’t. I said - and I probably did not word it specifically enough - that they once showed him hosting a show in 1961, which would mean that he is now around 70. They have not aged him or any other character in real time.
They haven’t been consistent on his age or anybody else’s, and they make jokes about that on a semi-regular basis. They showed him hosting a TV show in 1961 during an episode that aired in 1994, and in 1993, he said he’d been on TV for 35 years (but in another episode he did his 29th anniversary special). What I’m saying is that they have not aged him consistently, but having him be over 60 was sort of consistent with the backstory from some previous episodes.
they can’t age the characters on the show, the plots would be too contrived to keep Maggie, you see how they’ve had to stretch it with the future episodes they’ve done.
I see what you mean now. Probably they often just want to have the flashbacks evoke a certain era without too much regard for how old it would actually make the characters involved. One of the weirdest episodes for this is “The Day The Violence Died”- if you pay any attention to the dates, Chester Lampwick is in remarkably good shape for a 90-something homeless guy.
They even do that in the other future shows. In “Lisa’s Wedding,” the world jumps forward 15 years, so Bart is only supposed to be 25 years old. Instead, he’s depicted as a twice-divorced schlub (and drinkin’ buddy of Homer) who looks closer to 50.
One of the show’s main problems involving flashbacks is, they tend to put specific dates on them, and then they end up contradicting each other.
For example, Lisa was born during the 1984 Summer Olympics, but in a later episode, Marge was in college (and hadn’t been pregnant with Bart, much less Lisa, yet) from 1990 through 1994 (which also contradicts the “fact” that they graduated from high school in 1974). Also, in a number of Sideshow Bob episodes, when they “remind the viewers” what he had done in the past, they set specific years to the events.
Of course, they have already explained (in another episode) that it is a “show within a show.”