Photos, when it imports images, puts a copy of the image into a database which it controls. It then offers to you to delete the original file, from which the import was made, so that you don't have two copies, one in the database and one outside. When you say. "Obviously I move imports to a specific folder" do you mean that you put the images IN Photos into folders IN Photos, or that you put the source file into a folder OUTSIDE Photos? If you let Photos delete the source image, it will delete the file from which it took the import but keep the copy IN the database. Now, if you imported from somewhere and then moved the source file to a different folder, Photos won't know where you moved the source, so it should not delete that moved file.
Hope that helps some. It's a bit complex given how Photos works.