I’m trying to remember how they got the right to the Detroit area though. I think it was either in negotiating for the Rough Riders. Since they bought them for $1 (while taking on existing debt), Detroit area rights may have been thrown in.
Among the many mistakes they made the second time around was hint that they were going to move training camp to a University in Michigan, which led people to think that they were looking to move the team. The issue of the G-Men’s “ownership” of the Detroit area came up again at that time, so I believe it still applies.