Except it isn’t – neither the Scorpio bit or the Milhouse one being discussed in this thread, or for that matter literally any other example the Simpsons fan community sees in more than one way. We know because the writers have twitter, and get asked about these things pretty often.
More often than not, the first time it’s brought to the attention of the person to actually write the joke and/or was in charge of that episode and/or season, their reaction is pure confusion that anyone could see things that way. Less frequently, they find the same kind of wonder for the ability to interpret lines in more than one way that this subthread seems to have but which simultaneously makes it apparent they either weren’t in the room when it was written or just like the fan interpretation more.
The rest of the time they explicitly call it a case of fans overthinking a joke. Hank Scorpio throwing his shoe is one of those, unless the showrunner for season 8 was the first person to misunderstand it. This one isn’t even ambiguous enough to have been brought up like that to the best of my knowledge, but everything about this discussion sounds like the product of people overthinking something they first heard in childhood for maybe a few minutes per year over decades.
It would be pretty surprising if this turned out to be the only line in the show’s history to actually be written with multiple equally valid interpretations while also just happening to produce extremely similar results to everything else Simpsons fans have overthought in the exact same way but were wrong about.
I do not know that it’s possible to find a single example of a Simpsons writer acknowledging that a line was intended to have multiple valid interpretations like this. It’s literally just that fans of this show have typically been fans of it for a very long time, children are stupid by nature, and once you get an interpretation of something in your head it tends to stick even if it’s one that intellectually you should be able to recognize as a product of points one and two. Especially if you overthink it, because that allows you to build up justifications for why it’s right and/or makes sense.
It happens to everyone, all the time, but the simpsons fandom would be a lot more bearable if people just recognized this was something they’re doing rather than digging in their heels and insisting that some complete nonsense their brain invented before they could read is an equally valid interpretation, if not the only valid interpretation. When there’s an obvious reading of a joke and seemingly another deeper / better version if you look at it long enough, in every known example the first one is what the writers were going for.
Oh well, at least you didn’t go with the “That’s where I’m a viking!” one as your example. That is literally the most insane thing I’ve ever seen or heard, to the point that none of the unmedicated schizophrenics I’ve known have ever said or done anything that approaches it, and one of them was convinced the ghost of Jim Morrison lived in our walls.