This is tricky because it's not just one offender. Society's judgment of what comments are and are not acceptable is badly miscalibrated. LW's response seems fine to me, but I'm not surprised that others find it rude because they don't realize the initial comments were rude. I would suggest LW set a hard boundary with repeat offenders and develop simple deflection techniques for one-offs, but I doubt there is a genuinely good solution for what really is a pervasive social problem.