And it's exactly because the people engaging in this behavior know and disregard the "rules of engagement" that it's important to let them know that they will have more to lose.
And the way you do that is by stating it publicly, making YC itself accountable to the public and forcing them to actually act. That way, it's harder for such investors to convince themselves that when push comes to shove, YC wouldn't actually do anything.
And it's exactly because the people engaging in this behavior know and disregard the "rules of engagement" that it's important to let them know that they will have more to lose.
And the way you do that is by stating it publicly, making YC itself accountable to the public and forcing them to actually act. That way, it's harder for such investors to convince themselves that when push comes to shove, YC wouldn't actually do anything.