I find the timing strange and terrible, too. You're right on the order of events there. Why would they leak the information before the announcement of the release date, and an official announcement of their leaving? And while I know Squad is known for letting Reddit know anything before the forums, this was not a Squad post, but a post by the former devs. Why didn't they post here instead?
In fact, none of them have posted anything since. @Arsonide, @taniwha, @NathanKell, @sarbian, @Romfarer, @Porkjet and @Mu were online since then, but they haven't said anything (granted, Mu has barely said anything ever...). @Claw hasn't even been around since. That's what worries me the most. Is it something so bad they felt like leaving?
I see what you did there, and you are absolutely right.
I'll also take note they're all still marked as "Squad Staff" on the forum.