Creating a mess and leaving it to other people to clean it up. It's littering. Even if someone is paid to clean up your litter, you shouldn't litter in the first place.
I think the disagreement here is that this is litter in the first place.
My take is that PR overreacted. They thought it was a mess, and they thought they needed to do Serious Damage Control or whatever. But they were wrong.
This was a well done hoax. A more competent PR team would have leaned into it and showcased how Microsoft isn't just a cold corporate monolith. That it has a humorous side, or is more "human", or whatever.