/splay stop is perfectly valid and available.
/splay stop should not be necessary when using a haltdef, and further, it doesn't work. I'm guessing you didn't bother trying it before posting?
on ^*:INVITE:#test0000:{ haltdef | splay stop | join # }still beeps. even if it worked, it's an improper workaround to a
bugsee my
thread for even more invite event bugs