Just coming across this now myself, and yes, this makes no sense. I've removed the Montana location, which was locked in on the profile.
I know the Mohegans a lot better than the Pequots, but my understanding is that Tatobem was betrayed and killed by the Dutch in Hartford. This entry roughly matches that story -- it says Sassacus took over in 1633 after his father was killed.
I'll see if I can find something definitive and get it added. For now, I'll set the death location as Connecticut.