He doesn't swim naked, so he takes the summon anyway.
"Because a lot of people have died today, entirely too many, and while if you absolutely have to kill people your choice of targets is not bad, I doubt very much that you absolutely have to kill people."
"Yes," sighs Cam. "Yes, I am. Your civilization was rigged to explode as soon as it met someone it couldn't kill, and it can't kill me."
"I don't want to destroy you but under the circumstances I can't trust you, so leaving you alone will have to wait until I know more about what you're up to."
"I want to learn more about what you want to do, if it's not 'destroy filth creatures'. And I would like you to stop killing people. Maybe they're all so obsessed with purity that they'll kill themselves, but if you help them that seems like it risks bycatch of some who do not in fact want to die."
"So you don't think you can hold order under conditions where organized dissent exists?"
"Of course you are. This planet compares very favorably to the black holes. But you don't seem to think you could keep doing it if you didn't kill the purity-keepers?"
"Please just tell me what the prophecies say. This conversation will go faster that way."
"In the realm of public action the prophecies direct that we must sacrifice the purity-keepers on the first day. After that, their former functions will be taken over by related institutions or abandoned as unimportant. Their contribution to maintaining public health was more ceremonial than practical anyway."
"Well, a theological interest group seems to have taken over the planet," Cam points out.