Private businesses should not have any interference in what language they use for their signs or their conduct of business. It is PRIVATE business.
Taken to its conclusion, this is what gets us to having ROP neighborhoods, as exist in Europe. Businesses with Arabic only signs and spoken language, and no incentive for these "immigrants" to assimilate to the local culture.
Fine. When they call 911 to request emergency services for a heart attack victim and the EMTs can't read the sign to determine they have reached the location, they should have no legal recourse against the city for inability to respond.