Expressing qualms about hiring somebody who has voluntarily demonstrated a lack of ethics isn't 'being an asshole'. In fact, it's usually a good business decision and always an ethically-sound one.

Here's a sample question, feel free to use:

"If somebody offered you money to build the brains for fully-autonomous killbots PLUS mass domestic surveillance of the civilian population, would you accept the offer?"

"Yes" => They are unethical => No-hire.

"No" => They did do that, and thus are a liar, and thus are unethical => No-hire.