I agree with you on the idea that he doesn't have the legal rights to change locks & enter homes; that's what legal procedures are there for.  I also don't think his scheme would work in Mass because I believe that the adverse possession statute requires 20 years of open, notorious possession which might be why I haven't heard of similar schemes happening up here.  In a perfect world the cities would be taking care of the properties & billing the banks who own them (who would actually be paying their bills) in order to maintain property values for the rest of the neighborhood.  In a really perfect world, the banks would be selling the properties at a loss, just to get them off their books, but that's not what appears to be happening. From what I read in the article his purpose is to offer shelter to people who wouldn't otherwise have it &  I believe  that any time  kids don't have to sleep in a  homeless shelter then that's a good thing.