This is not just ab-initio, like U.S. airlines did briefly in the '60s when they didn't have enough applicants. That would not require any approval from anyone, they would just train people through all the existing requirements. JetBlue is asking for approval to take people rapidly through the process with no actual flight time, all simulator training. In Europe they have a similar program for MPL pilots, they are only certified to monitor the aircraft inflight. They are much cheaper to train and keep qualified, although still not cheap, and they are trained only for one airline, so they can't move to another, better paying airline. In theory, that should keep their wages from rising above whatever their airline chooses to pay them.
The difference is, JetBlue wants them to be licensed as actual pilots, not just cruise pilots, wants them to get their ATP after 1,000-hours of "flight time", monitoring an airplane next to a real pilot.
For now, JetBlue is setting up schools and smaller airlines to train up pilots in a pipeline to JetBlue, but the students have to pay all their expenses, which can be $200,000+ at a lot of the big flight schools. The airline industry is still trying to avoid spending a dime on keeping themselves supplied with pilots, and trying to keep new pilots as cheap as possible.