The tag is just as secure as the airline tag. Disney checks the unclaimed luggage area, will find your name on the DME list and will ship it to your resort. There might be a short delay. You tell the DME CM how many bags you checked and they'll look for the missing bag(s).
If the airline tag and the DME tags comes off the airline will look to the extra tag you put on the bag. You might put your cell number on the tag.