Are there other examples of suspects being granted asylum by a foreign government? It seems to me like that wouldn't be very likely in a vast majority of cases. It seems just as reasonable that DOJ needed to wait until Ecuador had dropped asylum and given the green light.
It seems like a stretch to say that the timing alone proves this is politically motivated when there were extenuating circumstances preventing the indictment. If you think the political landscape or future charges have a possibility of swaying Ecuador into discontinuing their grant of asylum then this seems like a pretty reasonable course of events.