DISCLAIMER: This Is A Bulletin Board and RHETORICAL Questions will get replies...particulary if you don't understand the organization you may be writing about...
First, SWA isn't the only major that allows employees to give feedback on prospective employees. SWA may give that feedback more weight than other majors, but that is speculative at best.
I have several friends at FedEx who wish they knew "XX" was interviewing before being offered a job as they would have provided feedback on this individual. Unfortunately for FedEx this person is now part of their team, and will bring the same character flaws to work there. I guess changing your name multiple times has it's advantages.
Second, and more importantly, hopefully you've considered there are other factors besides the ones listed which would cause a pilot to provide less than flattering feedback on a prospective employee to a company...i.e, they have flown with the pilot and found him or her to have poor judgment, flying skills, CRM, or what they might consider a poor attitude.
SWA understands that having employees who have spent months and years with and around a prospective employee enables them to gather additonal inputs to whether or not the prospective employee would or would not make an overall positive effect on the company.
Who knows maybe SWA might ignore the feedback of just one pilot who gives less than flattering feedback and consider the case isolated. But when five, seven, or ten pilots take the time to provide inputs about someone they don't want on the team...yeah you bet....that's gonna get noticed.
Yahtz