If the people living inside were reasonable and took care of Treyton's property, then it's actually good as they don't need to clean it up themselves.
Such a large area also required cleaning for it to look good, so if those people living inside actually took care of those chores, then it's good.
They only planned to rest in the mansion for a day or two before traveling again, so as long as the people they met are people that could properly communicate, then there won't be any problem with them.
Treyton doesn't even talk about his properties that were scattered throughout the country, knowing that most of those properties were already useless to him because he couldn't use any of them with the sudden appearance of zombies.
Treyton surely doesn't care if people are living in his several properties because he wasn't able to use any of them at all, but they're still his property, so of course it's good to use it if they could. If not, then it also doesn't matter.
