It's all about risk assessment. The airlines are concerned about cost and risk when it comes to handing out expensive training. The obvious interview question that would arise should you have failed/ given up on something major (like a degree course) is how do you demonstrate your ability under pressure/ stress etc. They may well ask you directly about the course.
The main thing to remember is to allay their fears of you failing their training or perhaps giving up. As long as you can demonstrate this and hopefully turn the negative into a positive I don't see it as a problem. I think the biggest problem would be giving up as that will take a bit more explaining. Best to check with CTC first though.
Best of luck
PP