That movie had a lot of different writers, so it’s tough to nail down what their exact contribution was, but they’ve still got that superhero experience.
The two are already used to working with a fun superhero, so it’s not some tragic tonal shift for them.
It also helps that with his humor and youth, The Flash is basically the Spider-Man of the DCEU.
They’re also one of the writing teams that contributed to the screenplay of Spider-Man: Homecoming.