Except they have. I live behind MK. I drive past it almost every day (and night). There is NO active construction inside the building.
Smells fine to me. It would actually make ALL the sense to halt construction. We're still living in a Covid world and they don't want to draw a massive crowd to one small part of the park. Also, Walt Disney World may be making a little money, but it's part of a division of the company that has been losing a lot of money for more that 10 months now. Keep in mind that attendance is still limited and nowhere near what it was a year ago. Additionally, the money they are currently losing by continuing to maintain all the closed resorts is pretty serious. Spreading out the cost over time might not make sense to you, but it makes a LOT of sense to the people who control the budget.
An aluminum panel is not what I'd describe as an "actual wall." It's a thin veneer that was applied to protect the building from the elements and can easily be cut open once work resumes. It most likely would have been waste material anyway. Plywood would likely have been more difficult, costly, and unsightly to attach.