Are you really limiting the pool? Do we want justices on the Supreme Court of Canada who are open-minded and knowledgeable about Canadian values? Is knowing the language or having an interest in learning the language not precisely one of these essential values we must promote?
Among the pool of qualified candidates, the fact that an individual shows intellectual curiosity about the other official language or both official languages is a sign of a competency which is perhaps even more important than others, when the time comes to choose.