It sounds like he’s simply stating what he would do to defend him. The ethical thing, for the lawyer to do, is defend his client, not help with the prosecution.
Of course, and that is exactly what the liberal media said about Hillary Clinton's work on behalf of the alleged perpetrator of a violent rape against a 12 year old girl. Clinton may have stepped over the line in her advocacy, using tactics and attacking the victim in ways that are now considered inappropriate. But no one in the liberal media said that disqualified her from office, as they are now saying about Labor Secretary Acosta, or that it indicated she was guilty of something.
Alan Dershowitz is a very skilled lawyer, and it would really be surprising to hear that he was personally involved in any inappropriate behavior of the sort alleged of Mr. Epstein.