Metal is not rubbish. Not everyone's cup of tea, but no need to generalise;) .H ow long has he being seeing the teacher .?
Is it a paid teacher, or school teacher? What he could do, is ask teacher to learn him one song that he likes.
He should incorporate that with his ordinary lesson.imho.
What does he sound like, when you hear him? Could he do with an effects unit for motivation?
He could learn bass also. Why not ?