I think cost considerations was major part plus the inconvenience of the flight crew of a private jet. I assume the plane she was on had a first class section and she did not appear to be in that area. Also, the cost of a private jet across country is costly. Finally, the pilot and crew of a private jet would be separated from their family if they waited for her return flight.
There are seats with more leg room on select flights but I don’t think that JetBlue planes generally do have a first or business class section.