They could have literally made up brand new characters rather than using the Rescue Rangers and nothing in this premise would be changed. Unless there's something way more intrinsic to them than what the trailer suggests, like Gadget has gone off to join that real life cult in Russia that worships her… and even if they DID do that, its so insane and out there that despite being real it might as well be a movie invention.
Galaxy Quest worked doing basically the same thing. You knew Tim Allen was supposed to be Shatner, it didn't need to ACTUALLY be Shatner. Avenue Q is a rauncy send up of Sesame Street but it has proxies making all the obvious jokes, you don't actually have Ernie having gay erotic fantasies and Cookie Monster singing about porn.
You don't have to tarnish actual existing characters to do stories that look at them.
Heck, take something like Watchmen was about the Charleston characters (like Blue Beetle and The Question) and examining that in a new lens... but without messing with those actual existing characters. By making them actual new one step removed characters, it allowed it to stand on its own and be something other.
If Zach Snyder, instead of making Man of Steel, had made Man of Meteor, and done that exact same movie, without ruining Superman in process and completely failing to understand the character, it would have been a much more interesting deconstruction.
I fundamentally disagree here; If the premise is to skewer the current Hollywood state of endless nostalgic IP revivals every property imaginable, a trend which is now creeping up to the 90s, a decade which constitutes the childhood of a major money-having movie-watching demographic segment…then grounding that movie in a specific, actual IP from the 90s immediately lends more power - and lets face it, generates more interest- for a satire of the reboot craze. Making the premise "An overblown modern reboot of Rescue Rangers! Isn't that a bit silly?" immediately underscores your thesis more than "An overblown modern reboot of [property we made up as an proxy for trends you hopefully recognize]! Isn't that a bit silly?"
Saying that actual IPs would be off-limits for a project like this because they would be "messed with" or "tarnished" is just so stifling, and limiting, and hard-gates what you are """Allowed""" to do with any existing brand. New takes don't ALWAYS work, but a "bad" new take - or a take one personally dislikes - on an IP is totally cool, because otherwise you'd never get a "good" new take on an IP that you personally like.