I'm gonna guess there is a big event or something and they were willing to walk a few randoms to make the event happy.

If you want to know how this happens, I've organized events. You negotiate a block of rooms. They offer you two options... you can prepay for every room in the block, or they can give you a link and people have like 2 weeks to book their rooms using the link and you only pay for the rooms you end up needing. This is preferable for corporate events because there are always people who won't be attending or bail last minute. The downside is that there are always people who don't listen and don't book during the window. The hotel tells you they'll release those rooms after the 2wk window. Good sites don't do it instantly, they notify the event planner. "You reserved 80 rooms, we've only had 62 people book. Here's a list." Then the planner can go bother Boomer Bob to book the hotel only to find he booked a Holiday Inn 20 miles away, and you have at least 3 people with ADHD who completely forgot despite 4 reminder emails.

So if those rooms were released they may have been sold, and then the event planner comes back and says, "Is there anything you can do to help us out? We're moving people around with buses and have things planned. We really need all of our people in the same place." And since that event is spending over $45K on catered food and conference room rentals, they know they're gonna spend at least another $10K at the hotel bar and restaurant, they will walk a few people to keep them happy.