He hadn't considered it- he didn't want to consider it. To put something that pure, even on a demon of dissent such as Zira, was going to hurt worse than physical death. His mouth set in a thin line, but he nodded, as he leaned forward to give Aziraphale one last kiss.
Tangled up as they were, it took Crowley a moment to separate them, sitting on the bed for a second to evaluate the damage in the room. He left it, for the moment- it didn't feel right, to will things fixed, before things were resolved. To that end, he moved to the phone on the nightstand, dialing down to the bar. A few quick orders later, and one of the humans agreed to come up with a vial of holy water, from the one church on the island.