Folks just because John is the sole member of the LLC that may have nothing to do with the "rights" of Halford's material.
It could just be a legal Company that was established for legal protection, but Halford most likely kept rights to many of his other Companies listes in the suit.
An LLC is set up for legal protection and some tax benefits - that can be very different that ownership of material.
At this point we don't know.
The fact the John is trying to "pierce the corporate veil" shows he is trying to prove that Halford and his other legal vehiles have becomed blurred in their separation.