TG are still losing money. They would be better advised to get their house in order rather than launching/resuming money losing routes to the US. The only reason to fly it is for ego/prestige reasons. There is a reason SIN is the only city in the region with direct US flights
PR?
But I agree otherwise, TG would need to have sufficient paid premium cabin flyers to make the economics working. Given the largely leisure flying demographic, it would be an uphill battle even with government approval at some point in the future.