It's the fact that so many people on here don't give anyone at all the benefit of the doubt at first.
Some of the assumptions that have been made regarding the man's intentions are ludicrous. It might have been the start of a chat-up, but it might have been because he was thinking of what to buy his wife for her birthday. We don't know! I hope those PPs are never called to sit on juries ...
If someone - male or female - approached me simply to strike up a conversation, even if I was really busy I wouldn't ignore them straight off. I'd smile, but say that I was in the middle of something. If they were really persistent, or I felt uncomfortable, I'd have no hesitation in moving away - or telling them to fuck off & stop bothering me if they were being really creepy/unpleasant.
But to just completely ignore & blank anyone who approaches & says something to you - that is rude. And, as a PP mentioned, they could be trying to get your attention because your jacket has fallen on the ground, your water bottle is leaking etc etc. That sort of thing has happened to me before.
I also dislike the ridiculing that takes place on MN around the words "nice" & "kind". I'm not a wet lettuce/a drip/a pushover - I simply think courtesy & decency are important qualities. I'm not deferring or kowtowing to men, or any outdated patriarchal notions of how a women should behave. I'm an outspoken feminist to the core, & passionate about fairness & equality - yet I also believe that kindness is a desirable quality in any human being*.
*And an essential one if I am to like & respect them.