oh I agree if this artwork was only for himself, but as he just dropped bucks for a wacom which ain't cheap, Im assuming he wants more out of his art than just personal statasfaction. Andif he does then that means hes gonna someday come into contact with editors, as in "if I don't like your work Im not going to pay you" and then the excuse of style wont save him, or anyone to that matter.
See to me there is two tpyes of style, there is personal style, and your going to have this no matter what, this is how you hold a pen, how you make a stroke basicly how you draw will come across in the painting, and then there is open style like manga, western, watercolour-ish, heavy painted, soft colours, hard colours etc etc and a good artist should be able to work with all the open styles, if you draw manga you should still be able to draw western art, if you draw furrys you should still be able to draw people.
So no its really not subjective, there is such a thing as good art and bad art, and anyone who tells you different isn't paying you.