A x A,
The only thing I can think of is a Part 135 operator like Contour Airlines (or similar). Not sure what TP operators they mean. Maybe "heavy" is a comparative term like a SA227, heavier than a C208 ?
Here's a Contour ad:
"Be a U.S. citizen or upon hire
show proof of right to work in the U.S."
I think I remember seeing earlier Eagle Jet Int'l ads promising green cards.
https://www.glassdoor.com/Job/indian...SEARCH_RESULTS