There’s nothing “moving” about a nightly wrapper. It’s versioned so you pin to one specific day. It’s perfectly safe to use, the nightly is only published if it passes extensive automated tests.
Also ASM is only required if you run the Gradle daemon itself on Java 11. If you only run compile/test tasks on 11 while running Gradle itself on an older Java version, things should work fine. So it’s mostly a convenience/efficiency issue, not a blocker