That single act would utterly destroy Islam, since it would prove to current muslims that Allah is a false god. They would - if they persisted - have to pray to a proven false god and toward a stinky radioactive spot of glass - how humiliating for them!
The pig crap should be added after while still warm, since that would insure a lasting, odoriferous ‘baked-in’ effect, rather than vaporizing it during the glass making operation.
Why this is a good idea: since in Islam Allah determines every single act, thought, and molecular movement, Allah would be proven false, weak and utterly incompetent. No one would believe one word in the book formerly known as the koran.
If they didn’t kill apostates there would be a mass exodus of the muslim faith.