>"'Oh my God, this is a sexual harassment claim waiting to happen!' That was my concern," she recalled
More generally, there's a tremendous civil liability, both personally to the principles involved and the firm, through such activity. A liability which may be entirely independent of the apparent (or actual) consensuality at the time, and which might be filed by non-participants (e.g., other employees perceiving sexual favouratism or discrimination).
A principle function of a corporation is as a risk-externalising, and limiting, legal structure. (This is literally stated in some forms of organisation, as with an LLC: limited liability corporation.) The principle job of management and oversight is to maximise the reward-to-risk ratio.
Company founders openly and documentedly treating the employee pool as their personal coital resource is a risk in the extreme.
The attempts in recent years by a small group of feminists to broaden the definition of non-consensual sex to include "I had sex with that rich guy because he could give me an attractive job but later regretted it" just degrades everything, especially women. It causes people to stop believing them when they say they were coerced by a powerful man. After all, Weinstein's accusers settled, didn't they? And his ex employers picked up the legal bills. Rumoured to be because he had tons of evidence that the complainants had willingly accepted their side of the "deals" and that such arrangements were commonplace throughout the industry.
Don't get me wrong, I'm not justifying sexual harassment in any way. But it's not "harassment" if it's wanted and consensual, and it's not _automatically_ unethical if the employee is not in his chain of command or even if they are, if they aren't forced into it, and there's no punishment for declining. If they make advances on their own and are merely not turned down (see e.g. Rosenberg, who IIRC wasn't in his chain of command), that's stretching the definition.