Weird questions are put to all teachers; one of those put to me strikes me as amusing. I was asked if a long tongue was a handicap in the pronunciation of vowels. In all my experience I have never heard of a singer with a tongue long enough to interfere with his singing. Even an average tongue may be dangerous if indiscreetly wagged in conversation, but no tongue should interfere with vocalization. In fact, the tongue should be mentioned as little as possible to the student, as indiscriminate suggestions may cause the unconscious stiffening of that member.
Any number of strange case histories come to my mind; discussion of them may serve to clear up some of your problems.