RU's struggles in Canberra, and the country more broadly FTM, are almost completely self inflicted injuries, and had little to nothing to do with RL. If anything the AFL has been more of a thorn in RU's side in Canberra than the NRL, and you'd struggle to find any ex-Brumbies fans at Raiders games aside from those whom always had an interest in both sports and the completely shameless bandwagoners.
In other words the Brumbies would still be struggling even if the Raiders didn't exist at all. It's also only just over a decade ago that the fortunes of both clubs were more or less reversed, and it wouldn't take much for the Raiders to sink back down to that level.
Describing Canberra as being 'back in rugby league hands' is not only reductive, but just flat out wrong. Canberra has never been a RL city in the sense that Sydney and Brisbane are, and likely never will be.
Aussie Rules is the sleeping giant in Canberra, and if it ever wakes up it'll be as big as the Raiders, if not slightly bigger, from day one.