The idea of a cutaway gag like in DP2 to Dark Phoenix's cast, but instead it's like... Chris Hemsworth's comedic Thor... There's potential there.
But yeah, even if Once Upon a Deadpool worked, it worked in spite of its rating. Hopefully Di$ney is $mart enough to $ee how much ca$h they'd lose going PG-13.
The other side of the coin is that DP1 and 2 made fun of Fox quite a bit, and comic book movies in general, and even took potshots at the MCU. Will Disney continue to allow that?
Keep in mind Disney censored a joke about Keylo Ren in one of their own movies (Wreck it Ralph 2) because at the time they wanted to build him up as some unimpeachable badass like Vader, even though it was clear to everyone from the outset he's just a whiney fanboy.

Since it's Marvel Studios and thus Feige, I'm sure Reynolds has a ton of leeway, and in fact he probably wouldn't even do it if he was shackled in some way. But I still worry about script notes such as
"This skit about Han Solo's son making out with Palpatine's granddaughter is too over the line."