Now if Disney was signing my paychecks, I could probably make a semi-coherent argument that a hoodie/legging-clad woman with spider powers is ok, just as long as we don't specifically call her "Spider-Gwen."
Mouse actually tried that once before during the Iron Man II premiere with a live appearance by the Iron Patriot, despite Rhodey/War Machine clearly being in the Avengers family. (And I guess he was Norman Osborne in the comics--but again, Spidey family.) Never heard of any blowback, but it ended up being a one-time appearance.
Again, there are very few obvious answers here--the contract was written to reflect a very different situation than the one that exists in 2018. I do think, because he's "Spider-Man," Miles is off-limits ... but the lawyers who drafted the contract never anticipated that Spidey's dead girlfriend would one day be resurrected as an independent superhero possibly with her own movie (let alone that Disney would own said character, and even contemplate including her in their park).