It could come down to poor decision making that sometimes comes with age.
Or possibly just not being able to keep up with the ever-changing "acceptable" vernacular. Which of course is the exact reason it's ever-changing.
Anecdotally, claims of "harassment" from older men I've seen are around comments in the vein of "Well, you're a lot better looking than most of the gamers around here." Those claims might hold water, for example, at the workplace -- especially if they come from a supervisor -- but at a gaming convention or any other purely
social event? Seems like "flirting" to me, and it seems like some people can no longer tell the difference. "Harassment" has come to include any comment from someone you find unattractive (disclaimer: I have no idea how attractive Frank is).