Truthfully I can't remember the specifics as it's been a number of years now since I dealt with the matter. Usually there are agreements between jurisdictions so people don't fall through the cracks. Although more common in aviation, this matter comes up quite a bit in other industries such as construction as well.
Usually, yes, the initial claim should be to the province where the person works. Sometimes though, the two provincial boards don't communicate too well.
Again, I haven't read the whole decision, but it doesn't seem the validity of this FAs claims are really in question, more just a jurisdictional issue.