He's in a great area! I'm going to assume he will have a car, because you can't really get anywhere in mississauga without one. There is a lot of ethnic food in the area. At Dundas/Winston Churchill, there is a sushi restaurant, and a Vietnamese place that have a lot of options.http://www.benthanh.ca/store.php?page=1 ... ississauga
Around Dundas & Hurontario there are lots of Indian/Asian places.
He is close to Port Credit where Raw Aura is located. There is also a nice health food store http://www.planetorganic.ca/
where he can get some take out.
Technically he is close to the Whole Foods Market in Oakville (QEW/Trafalgar rd). During the day, it shouldn't take him more than 20 minutes to get there, but at rush hour, forget it. That area gets backed up in a really bad way. He could get there by taking alternate routes.
Zen Gardens is awesome, but is a good 20 minute drive from his hotel. Up in that area is Guru Lakshmi, south indian, fantastic Dosas. You just have to ask the server about what's vegan and they will tell you.
Hope he has a good trip.