Yup, he should have quoted from the Koran how to treat homosexuals.
Koran says its a sin. Hadiths prescribe the penalties, including death...
“Abu Dawud (4462) - The Messenger of Allah (peace and blessings of Allah be upon him) said, “Whoever you find doing the action of the people of Lot, execute the one who does it and the one to whom it is done.”
al-Tirmidhi, Sunan 1:152 - [Muhammad said] “Whoever is found conducting himself in the manner of the people of Lot, kill the doer and the receiver.”