Your post is a little hard to follow, but it seems like that guy was flirting with her, but she wasn't necessarily flirting back? Do you have evidence of her saying flirty things back to the guy who said he wishes he could be in bed with her?

And the stuff that happened two years ago? That doesn't matter now. What matters is how she behaves now.

If she is flirting and clearly crossing boundaries with other men, then yes, I would say there is cause for concern. But if she hasn't been, and men have only been flirting with her, then perhaps she hasn't really done anything wrong?