I am not an expert on this topic. Have only talked to a few "landlords".
But I believe that, if the landlord has a valid extension, and they are hiring Thai nationals for any "work" involved, and they are reporting their income to the Thai government and paying taxes, I believe it is all fine. The difficult part is proving you are not "working" if, say, you are on a retirement extension. But one guy I spoke with indicated that he hired Thais for everything, including meeting potential renters and executing all paperwork. Another simply had a management company to handle everything - I believe as part of the development.