Would it really, though?
I'm away from book, but don't the lizardfolk's crafted items only last for a fight or something? They're fairly fragile.
I'm not convinced a lizardman wizard who crafts himself a shield a few times a day is really that OP. He could get similar/better armor options via multiclassing, feats, etc. without those being overwhelmingly advantageous. Lizardmen don't make great wizards, otherwise, so this would just be a sort of nifty little bonus.
I dunno, I'd be inclined to allow it.