Every player on the Golden Knights that was waiver exempt was sent down because they were waiver exempt and allowed the Knights to keep another player on the roster that was not waiver exempt.
Also, his talent wasn't shining in the preseason. I still think his waiver exempt status was the main reason he was sent down, but there's a decent chance they just wanted him to work things out in the AHL. He was not great in preseason/camp/practice.
I don't think we emphasize this enough. He came in expecting to be entitled to a first line position. He didn't come in great shape, he didn't work hard at getting into great shape and obviously was spending a lot of time and effort on the "acclimation" phase for himself and his family. All sounds nice, but this is the NHL where there are rookies and veterans alike working their butts off 12 months a year just in the hopes of getting to stay on an NHL roster and getting draw in a handful of games a year. They go hard every practice, show up prepared for every team meeting, show their dedication in the gym, and even then many don't get more than a cup of coffee with an NHL team. Even if you proved you are elite in another league, I don't think anyone disagrees that you should still show that kind of hustle and determination to continue to deserve your place among the world's best. The elite of the NHL could certainly try to coast, but none of these guys do. You hear nothing but of amazing work ethic and constant push to make themselves and teammates better. They know no other way. Shipachyov was nothing like this and if it didn't get him in trouble this year, it probably would have in another year with another team.