As someone who has worked in hospitality in the past, my issue with the lanyard is that if it's for all hidden disabilities, it doesn't really give me any guidance on what, if any, additional assistance a guest might need. A deaf guest will have different needs from an autistic guest, who will have different needs than a PTSD one and so on (even guests with the same disablity may handle it in different ways). Even if a guest has a visible disability, I can't assume what all their needs may be. For example, they may need to use elevators, but don't need a handicapped accessible room.
I hate to put the onus on the guests to convey their needs, but with such a diversity of needs out there, it's presumptuous to guess what the needs may be.