1) Nick met up with someone we don't know about.
2) Someone who is afraid to be tied to Nick's disappearance or worse is the owner of the hoodie and is intentionally misleading his last description.
Food for thought:
I did not dig up this knowledge personally, so it is objective, I was told personally by a rep of TES that although sometimes dogs can be VERY helpful, their accuracy for hits, especially on campus, is very low. There are no less than 60 variables, and even then the margin of error is high.