Temp stands are extremely expensive alone, but now your adding food,trucks, washrooms,locker rooms, production facility ect. Your overhead would be much much lower in td place which is ready and willing for this type of event. Line it up with the Grey cup that I'm sure Ottawa is anticipating and it just makes way too much sense. parliament hill can host some festivities if need be. But Honestly landsdowne park was built for it. It also gives OSEG an opportunity to get any changes/upgrades (endzones what have you) paid for or partially paid for.
Parliament hill is a great idea, don't get me wrong! what a setting it would be. But the point of an outdoor game is too make money so if your building a one time use 30,000 seat stadium for 2 games you're probably gonna lose money. landsdowne has all the right stuff for such an event beyond the stadium itself,room for a stage for some locals bands or the 10,000 seat arena, a ton of empty indoor space with the old pavillion, a few out door rinks, it already has restaurants, coffee shops, hotels near by. no brainer for me

