I would waste your time on warranty. Its very easy to tell, the cut in your track is from a puncture, the fibers are sticking out of the track and the "cut" is not a clean, straight, line.
The idler wheel damage is more of a split from over time, and it will be in multiple places on the track and it happens slowly, with no or little sign of fibers sticking out of the track.
Back to your original post, you said you made a bad call. So it sounds like you know exactly what caused the damage.
I wouldnt worry about having to replace it. Burn the fibers with a torch, and you could also heat up a screw driver and sear the cut so it doesnt try to spread.