The idea that Colin and Voldemort were in the same league would certainly have upset her, and she'd have argued that quite adamantly. But since he hadn't expressed it, they were safe from an argument on that front.
"2003," she responded. "I'd offer to update you on those two years, but I'm afraid we didn't precisely have the same social circle." Luna hadn't really had a social circle at all in those two years, actually. Or the several preceding it. There was only so much a person could handle, and between taking care of her father and trying to support themselves, her social life had fallen rather by the wayside.