At least they are flying on Saturdays direct back-and-forth to SXM from Toronto. The Air Transat website shows them flying other days to Sxm, but those are not direct. They use Porter airlines to fly from Toronto to Montreal and then to Sxm.
I like Air Transat but I have been flying on all four airlines that fly direct from Toronto to Sxm. I have booked my November and September flights. Both direct. I am too cheap to pay for first class. My WestJet flight return and direct in September was $468 Canadian ($343 US). My flight in November again direct and return was $443 Canadian ($325 US).
I will probably be at the back of the bus 😂 with the entertainment, but it does show you can still fly relatively inexpensive to the island at least from Toronto.
I should mention that I do not have a check on bag. Just carry on.

Drphilsxm