@Michal-Rok Okay, you are a genius!
That is working, however, still unsure why setting it after connection changes anything.
Even more so, it appears that without setting mode sta it doesn't even appear to attempt to connect with the router.
Would really love to know what the mode flags do to the ralink device!
Using rc.local is of course the key to getting this working after the fact but I feel dirty leaving it as a proper solution.
Thanks to anybody and everybody that put effort in here, I think we have a (albeit, not perfect) working solution.
Can anybody else confirm this works on other MT units out in the wild?
I'm doing this on a 2011UAS-2HnD but I believe it should work on any unit of them.