I can't comment on how the SLC HR department works, but as someone who has recently gone through the pilot interview process I'll say that the only way that taking this job could hurt you long term is if you perform poorly. Take the job and show up on time every time, work hard, be friendly, and get good reviews at every chance. Keep a positive attitude. Oh, and network. You'd be suprised how many people will go way out of their way to help you out, but you have to take the effort to engage them, they won't come to you.
As far as transitioning to a pilot, they are looking for solid flight experience and also a well rounded person. Like others have said, you'll have to do flight time elsewhere to get qualified, but make as many contacts at Delta as you can while you are working there. If you can have several pilots go to bat for you, you'll miles ahead of the competition. Plus, you'll have Delta related stories to pass on during the interview. I certainly wish that I'd have had some "inside" looks into the culture at Delta for the interview (fortunatly though they still hired me).
Good luck to you.