Demonstrate that you are taking her experiences seriously and behavior like that exhibited by your new employee is not acceptable. Get him out of there.
Or, because corporate culture almost everywhere can be summed up with the phrase "don't rock the boat", gender notwithstanding.
There's no need to prejudge every woman as a victim - certainly one you know nothing about other than a one paragraph story on HN.
This is what's called benevolent sexism.
At one of my previous employers, we had a woman quite high up in the hierarchy (boss's boss, or maybe one more level) who regularly called on young male interns to "fix" her computer, which invariably involved them crawling underneath her desk...or asking pretty much all the inappropriate job interview questions etc. etc.
Let me paint a hypothetical: Idiot salesmonkey learns that hitting on a colleague doesn't get him in trouble. So he hits on someone else. They have an immediate bad reaction (as you'd expect) and the shite hits the fan. During the ensuing nastiness it comes out that the salesmonkey hit on the employee, who reported it, and that nothing happened. Immediate escalation of nastiness ensues.
Not a lawyer, but I went through an MBA where our legal lecturer had a lot of these sorts of stories to tell.
OP HAS to do something. Do NOT ignore, even if the offended-against employee can handle it and doesn't want to cause a scene.
What she's really saying is: "I don't want to be embarrassed and it would make me feel guilty if he was punished because of me, so I don't want to advocate for a course of action"
But she is right to have brought it to the OP. Now he is obligated to take care of it discreetly and professionally.
Additionally, you generally don't want ass-hats that do this kind of shit working for your company, when the other party has made if obvious the advances are unwanted (we can only go off what OP has said though) working for your company. Especially if its small.
That isn't a quote from the person you replied to and that isn't what they said at all. Not even ballpark.
You seem to be replying to a strawman argument rather than the person you hit reply on.
it protects her from trouble, and frames the dispute as between the founder and newhire.