It is relating to the issue of whether or not the national anthem should be sung in languages other than english, and as a language completely independent of english, ASL is an apt comparison to make.

Having two close friends who are sign interpreters professionally, I can tell you that one need not be "disabled" as you put it, in order to use it. It is a language of its own accord, unrelated to english in many ways--own system of grammar, etc.--and the community that uses it has a culture that is very divergent from mainstream American culture. In fact, many of its members would consider it to have a culture all its own.

The parallel seems logically consistent.