First, this is a lovely incident of truly good action and all concerned should be applauded for their actions.
Having said this, your comments, while well intentioned, are ignorant of history. Deafness and the need to communicate with those afflicted has been with us since the start of humanity. Every society / language group has developed their version of the communication because at least ONE PARTICIPANT is speaking / signing in their language. Thus the historical development is with language specific signing languages. It has only been in recent times that there has been an interest in developing a more universal sign vocabulary.
Dr. John McWhorter, the well-known linguistics professor, tells a very interesting anecdote about a home for the deaf in Central America. (I don’t remember which country.) The residents had no instruction - they were simply housed and fed - but they independently developed their own version of sign language that was unique to that one facility.
How am I ignorant?? You just stated yourself that there in interest in developing a more UNIVERSAL SIGN LANGUAGE!! HELLO!! That’s exactly what I posted! omg...seriously. what has happened here??