My take on it is that they should not ever know. That was the deal when they were born. However, this guy apparently wants to know, or he probably would not have submitted his DNA.
I have only third-hand (or so) contact with this sort of thing … it seems that using lawyers as cut-outs to make the first contact is the normal way it’s done.
I’m not personally in a situation like this (that I know of) … not at all sure how I’d respond if Larry the Lawyer contacted me regarding my previously unknown illegitimate half-brother from my father’s youthful fornication (or whatever) …