It seems to me if someone were to intentionally gather up thousands of maggots, transport them to some house and then dump them on the floor of someone elses house, almost too elaborate. Maggots stink too. I'd be pretty pissed.
It seems more likely to me that they hatched up out of something that was spilled in that room. So many people don't bother to think of their carpet and furniture as capable of being a breeding ground for bugs.