This kind of speculation is why it took so long for people to give much credence to the medieval Norse stories of Vinland, because they’re busy wildly theorizing a Chinese discovery of and settlement in Canada as in The Island of Seven Cities.
There are a few voices of skepticism in the discussion (this from the CBC):
David Christianson, an archaelogist with the Nova Scotia Museum, says while many things are possible, he doesn’t buy Chaisson’s [sic] theory. Christianson believes the ruins are more likelyan old logging road or a forgotten European settlement. “I think some of it is naturally occurring and … there are many more plausible explanations,” said Christianson.
And there’s a lively discussion over at Northern Blue Publishing.