That would be nice, but since the cow butter may not exist in large enough quantity, it's unlikely human DNA would remain in sufficient quantity (and quality). The cow butter wasn't ID'd at all, but is guessed to have been present because "a wide range of proteins in the pigment, including bovine albumin and casein" is present.
Maybe instead of getting the milk from domestic animals, they only made paintings after the successful hunt of a lactating cow elk or aurochs or whatever. I imagine a mammoth teat would hold at least a gallon or so!