Forum:DNA Surgery/Soulabsorbing bone towers

my friend has just played DNA Surgery, against my zombie deck, and made all types pyro. how does this work with regards to the second effect of soul absorbing bone tower. where each time a zombie type monster is summoned succesfully the opponent must discard the top two cards of his deck. the monster i'm summoning is a zombie until it reaches the field and becomes a pyro due to the effect of DNA surgery.

would they still have to discard the cards or does DNA Surgery negate this effect?

many thanks