the thing about squats and beginners is that they tend to do them without knowing how much weight to use, or without proper warmups, and like deadlifts, if you do them with bad form, they might hurt your lower back.
that's about all i could see being wrong with squats...otherwise a great compound lift for GH release, and great for the quads...tell your friend to warmup before doing them, and show him how to do them properly, and he will realise it's just a myth