Anecdata from other HN threads is the FCC doesn’t really go looking for these, rather it accepts cases wrapped up in nice little bows by pissed off HAMs. Maybe there weren’t any HAMs in range or he didn’t affect their bands.
I'd like to think, for all their promises of reliability, mobile phone carriers would notice a sudden hole punched in their coverage maps, since they can monitor the signal quality of each device from their central control as they move around the area, and investigate themselves or summon the FCC once they discover it's not natural interference.