Depending on the definition on suitable, you may be right. However, I think that your definition of suitable and the NHL's definition of suitable are very different. How many of these other suitable arena have the cameras and links back to the Toronto war room needed for video review? Do they have the broadcast facilities needed for producing an NHL broadcast? Do they have the capabilities for providing the promised online access to post-game conferences that the NHL has promised? Could they be upgraded to have those capabilities? In three weeks and at a cost that makes it practical for three weeks of broadcasts? I'm not so sure.
I can't speak for Toronto.
But I know in Edmonton, there's already 2 arenas in the ice district (one used as a practice facility).
Same with the UofA Golden Bears, and the Bill Hunter arena used by Grant MacEwan.
They've had broadcasts on TSN and Sportsnet.
I'm not 100% sure, but I believe Northlands Coliseum (Rexall Place) would still be usable.
It's obviously not ideal, but the Oilers were still playing there as late as 2018.
I'm sure there are plenty of other facilities. Equipping them with Cameras isn't a huge deal.
The issue with the arenas were always about things like capacity, availability of parking, infrastructure (public transit lines), concessions, washrooms, etc. But if they're playing in front of no crowds, 99% of their issues disappear.