My point is that it is not good for beginners to be playing marginal hands. It's really hard to get them to hear it and why it matters, though.
I understand where you're coming from, I mean it's better to be too tight and then slowly loosen up to optimal, than it is too be too loose and tighten up to optimal.

But if KJs and 66 are the worst in an UTG range, I don't see any reason for concern. In fact, I'd consider that tight for a beginner, and be impressed they're folding 22-55. I wasn't when I was a beginner.