I don't understand what you're saying. You say that an apology is an expression of regret, but then you say that Dell's apology isn't an expression of regret. Are you just saying that the Dell statement should have been more explicit?
I'm not sure he agrees that it is an apology.
I think it is more fair to say is that they expressed regret, but the only regret they expressed is that other people were offended by what they did. The conclusion is that if they had it to do over again, and they could find a way to do it without offending those people (keeping it secret perhaps?), they'd do it.
In this case, a honest apology would be one where Dell apologizes for hiring that moderator: if we could go back in time and hire a moderator again, we wouldn’t hire that person.
Maybe their apology for the offense is supposed to imply that (presumably, since they are apologizing, they want people to not be offended, one option for them to prevent that is to not hire people like that in the future), but why not say that directly?
(I think the view that offense doesn’t matter and can be safely ignored is extremely damaging. And besides, it’s not as though offense is the worst thing about this. Dell gave someone the stage who legitimizes very weird views that would be disastrous if they became – even more – widespread in society or even the basis for policy. That’s why people are offended. And that’s a very good reason to be offended. Yes, words do matter.)