Marriott are not "law enforcement." I get that they need to know what happens in their hotels, but why are they "conducting investigations," and issuing penalties (removing Irvin from hotel). Why not just let the cops do it?
Give a corporation a few big government contracts and they start thinking they are part of the government...
But The Guess Who once told us that “The hotel detective was out of sight!”.
With regards to hotel policy yes they are cops of their own property. Wifey works for a large chain and they will investigate if policy is violated, ie abuse of staff, disregard of hotel policies. Lots of reasons.
Actually hotel having their own security is pretty standard. And doing a quick check of available tapes if somebody complains is just common sense. And there’s no reason to involve the cops when kicking somebody out unless it escalates. It’s all very normal.
They at the least should have looked at the video and heard from their employees what happened.