You have to acknowledge (in full) what it is that you are apologising for. That's the most important thing. Promises are meaningless.

It's not possible to "be genuine"; especially in a public post, nothing is genuine, everything is PR and smoke. Both the researchers and their ethics board need to grovel. If they did that, this tornado-in-a-teacup could be over in a month or two.

But keep those researchers banned.