I think all O's have to have TS, but i'm not 100% certain. Secret for sure. You're given a great deal of responsibility and often times, very little oversight as an O. You can get away with quite a bit (and people have) if you're dishonest. Owing money, while not in and of itself a dishonest thing, could lead to problems later. I'm not saying you'd be like this, but people who have debt have been known to do things for money that people with less debt (or no debt) wouldn't do. Sometimes people get desperate and do bad things, despite being very good people. This is why credit is important. It can also be an indicator of reliability, organization, and prioritization.
I doubt $2500 would be even blinked at though. Many, many people owe that much to a credit card or whatever. It's when you have $20k, 30K, or 40K+ in high interst debt that they start to worry. House loans, car loans, student loans aren't a big deal, those are understandable. Besides, when you get to the fleet you'll see the nicest cars being driven by E-4's.