The raid being due solely to music copyright infringement is really the most likely situation. There's no need to imply it was anything else.

For example, in 2009 I worked at a record store that got raided due to such claims. The RIAA's informant claimed he had seen people selling hidden bootlegs, which absolutely wasn't happening, and that was all they needed to have cops raid the store, arrest several people and cart off boxes of not-bootlegged, sold-by-major-CD-distributors CDs. Court dates followed and the case was eventually dismissed (or settled due to being more convenient than continuing the case? I can't remember), but it still took time, money, and lawyers. And this was in 2009, when the recording industry wield less power than in 2001.

(I was running late for work that day or else I would have ended up arrested too, since I was one of the managers scheduled then. Thank god I was running late!)