As an instructor for a number of agencies I can tell you there has always been a concern about new divers getting "certified" in southern waters. NAUI used to insist that if a Canadian diver did his open water portion of the training in southern waters that the diver had to do one cold water dive to get his/her certification. This could apply to Bgs as being in Toronto and only 4 hours away from Tobermory..an area that has 25 shipwrecks with 8 sq. miles...Bgs might just want to explore one or more of those pristine wrecks..BUT..the water seldom gets above 65 and deeper down is in the 40's. Diving in water that cold needs special training. And yes, I've heard the story a hundred times.." Oh, I'll never dive in cold water!"
For a first open water experience warm water is certainly much better for a new diver because in open water the new diver has a lot to take in BUT we ( the instructor community) recommend a new diver at some point after open water checkout get at least one checkout in cold water.
I have been on cold water wrecks a lot and because they are in cold water they are almost totally intact and covered only with Zebra mussels as opposed to warm water wrecks in salt water which, after not too long a period, are almost unrecognizable because of the coral growth. AND a bonus..no chance of seeing sharks in cold freshwater....yet.