Peter’s polemic deferred direct attacks on Muhammad to win Muslim ears.

Evidence

Peter realized that to open the Contra sectam by directly attacking Muhammad would only provoke the hostility of his Muslim audience. Instead, Peter uses a few well-chosen Koranic citations to try to prove that Muslims should accept Christian scriptures; once he has done that, he can return to the exegetically based polemical method that he had employed in the Contra Petrobrusianos and the Aduersus Iudaeorum inveteratam duritiem. — John V. Tolan, Saracens, 869