I'll take them
Only way I can see them helping for your UA status qualification is if you can find a good mileage run that requires a positioning flight, you can transfer the miles over to another airline (UA or other) to book the positioning flights with miles.
Specifically thinking if there say a good UA MR that's ex-Asia, you could book that and then use Marriott ---> Airline to book the US ---> Asia flights in J
Or if MR requires overnight stays (which wouldn't make a true MR but similar thought) -- you can use MR to cover hotel.
And even if you are done with Marriott -- they still have a ton of very nice hotels and if you have a few hundred thousand points, why not pick a nice one and go enjoy yourself. Don't sweat the loyalty side of things -- but you can still go blow them on a nice property.