If it is true, it is only true for one of them, not all 24. The other 23 have been, quite wrongly, lumped in with the one the allegation actually focuses on.
When I studied law (many years ago), I recall the lecturer explaining that you cannot defame a group of people. Thus, the other 23 cannot sue for defamation. This reminds me of the brave newspaper editor who ran a front page splash along the lines of "Half of the council are stupid idiots!". Some councillors took umbrage and complained threatening all sorts of legal trouble, so the canny editor to his credit offered to make amends