He picked the wrong defense.
He should have said he was indeed making the hash oil, but it was to self-medicate painful injuries he had incurred during his years of faithful police service to the community.
Butane is dangerous.
It is heavier than air and will travel across the floor looking for a path of least resistance, like water does.
Far safer is the dry ice method, which will only rip the skin off any body parts it comes in contact with.