Serious question, does free speech apply in these situations? You have the unalienable right to speak your mind and some people may be offended but that is not illegal. I totally understand if you are employed by someone you can't easily get away if you are made uncomfortable but this is entirely a voluntary situation. Also, if you really think about it making something that makes someone uncomfortable illegal is wei…
Similarly, you can't run toward someone screaming, pull back like you're going to throw a punch, then claim innocence when charged with assault. There are numerous court cases that draw various lines. Courts have recognized people sometimes say "I'll kill you" but without any actual intent. They also recognize sometimes threats are veiled and spoken in coded language to give the superficial appearance of acceptability... but the threats are just as real as pulling back in a punching motion.
Much sexual harassment falls into the latter category. Rarely to abusers (male or female) come right out and say "sleep with me or you're fired / I'll tank your funding round / I'll call your loan", though that does happen. By far the most common case is subtle suggestions or inferences that things will be easier for you if you go along with it.
In general it is best to avoid anything that appears romantic whenever there is a power imbalance. As a VC, you shouldn't be hitting on founders. If you think there is mutual attraction there then send that person to a friend at a different VC or wait for the funding rounds to close and assign the company to a different partner. Even then it is risky - the target of your affection may feel like they need to play along or you'll start bad-mouthing them and it will crush their business. When the target of your affection says "Sorry, I have a partner / boyfriend / girlfriend" it is a very clear signal they are not interested.
Even better advice is: don't. There is a wide pool of potential partners. Why are you so desperate to find a pickup among your founders / subordinates? Hint: usually because you're taking advantage of them! In this case the most likely explanation is the guy wanted to have some affairs and thought hooking up with founders would be an easy score. What those women thought or felt was entirely beneath his notice.