His situation falls within an area of grayish boundaries that separate a gear rental agent from an outfitter or guide. The catch is accompanying your client in the field after he has rented equipment (as one example). The way the law reads I can rent a group their gear but I cannot accompany them or provide service for their field logistics. Companies can find legal ways to do both but it gets tricky and logistically challenging.
Howard Teiden of Arrowhead Outfitters for example: He was a pilot/owner of the business and rented his clients rafts and gear. To do this legally he had his wife establish a separate business license for renting equipment, she issued the gear to the customer and they drove North to meet the pilot (separate business license but really all connected). I can rent gear as a hunt planner as long as I don't handle the gear in the field for them or provide services in the field. Otherwise, activities can be construed by LEOs as outside the letter of the law.
Hook's a good dude and will learn how to navigate the law more as a result of this case. Stings when you learn a lesson that costs you that much and your intentions were not to break the law.