Joint venture doesn’t mean freebies. On Wikipedia (not the most reliable) it says they have free input gas, not sure what that means. I’m sure they have to pay certain fees/possible taxes etc. Related party transactions have carrying and exchange values which do affect financial statements per IFRS, so you can’t say free of charge. But we are talking accounting now not oil.
I doubt Qatar paid for the plant out of their pocket. It was Shell. Maybe they subsidized it? Before even putting drill to sediment they put paper to pen and probably used a discounted cash flow model to determine the NPV for the plant itself.
I still haven’t been provided any sources of academic research or tests which prove GTL > PAO or is equal to it. Do I doubt it? No. But facts don’t care about my gut feelings and it would be nice to see.