I mean, we all know I don't really think much of Griff but in this particular case, Griff is right. He said that people tend to think the offseason ends at the draft but it doesn't. Donovan Mitchell was traded in September to give another example.
Draft-day trades are most common but it's not like things never happen at other times. I hope we don't have to wait until September (even if BI signs an extension, I'd rather him get it over with early) but it's always a possibility.