Looks like the fare to Laos (VTE or LPQ) still allows the US connections for US$300 more roundtrip than original YUL-BKK fare. I was interested in continuing to Laos anyway, so considering it. Fare rules seem to allow TG or PG from BKK to VTE/LPQ, but matrix at least doesnt seem to price it without the QR coded PG flight.