I wouldn't read too much into this. SOP for most police forces is a tiered approach to seized drives. They plug it into a windows machine and see what's what. If that doesn't get the immediate results they have to hand it to the professional data recovery people. Even a cursory forensic examination of a drive starts at 1,000$ and may yield nothing if encrypted. With a small pile of drives to look at, they probably didn't bother trying after spotting it wasn't going to be plug-and-play.