Ask yourself: What does an airline cadet program do for you that you can't do yourself, and are the benefits it provides (a little money basically) actually useful or are they just bait on a hook to keep you from exploring the myriad alternate options for getting an airline career started? This program exists to trick you into signing a commitment with QX before you are experienced enough to know how many other options you have as a newly qualified ATP - that's the entire point of its existence. All you're doing by joining a program like this is limiting yourself to one option, when outside of this program's commitments you could go to the first/best company that calls you when you're ready - and even if QX sounds like a good deal now, who knows how the landscape of the industry, or your personal life, will change over the course of the ~2-3 years it will take you to reach ATP mins?

If you really want to fly for Alaska (and I'd question how you could be so sure about that at your experience level), and assuming the pilot hiring market continues like it is now, you will get here faster by NOT being slowed down by the pipeline program.