Risotto is usually a dish all by itself, with veggies and meat that's kind of a lot... but if you like it, your choice.
As for the Kangaroo, I would slather the loins with olive oil, bit of salt and pepper, that's it. Then grill or sear very hot for a minute or two until you get nice grill marks, and change the orientation of the loin by about 90 degrees, get your cross grill marks for another minute or two (hard to say depending on the heat and the thickness of your loin). Then turn and grill for another minute or two, and that's it. Rest for 2 minutes and serve.
The meat is really lean, so it will cook very, very fast, and you don't want it to overcook at all, you want to serve it pretty much raw in the center, like seared ahi tuna almost.
If you/your guests don't like raw meat, then you can finish it in an oven or turn down the heat on the grill and leave it a few more minutes, then increase the resting time a bit - but beware - lean meats are very very easy to overcook and dry out real, real fast.