He simply didn't remember it - and if he had he wouldn't have believed it.
To quote from the man himself, who was interviewed about this:
Question: The movie presents your character as either repressing the knowledge
of what was going on or not acting as strongly on the knowledge of
what was going on as you could have.
Answer: Yeah. Part of the reason for that being in the movie is that there was
a story the Globe actually ran in 1993. The Boston Herald also ran
this story, and both papers buried it inside, about this one lawyer,
Eric MacLeish [played in the film by Billy Crudup] who basically sent
out a press release saying that he had found 20 priests in the
archdiocese [who had been accused of misconduct]. Now, in truth,
looking back on it and knowing Eric MacLeish, that was Eric MacLeish
trying to get attention to himself so he could get more clients, which
he did. We published this story and we buried it.
When we started our investigation eight years later, that clip didn’t
surface. None of us remembered it. Back in 1993 I think I had been
metro editor for about a month when that story ran. I had no memory of
it, although I actually think I was on a golf vacation.
So the possible reasons he gave are above:
- Truly having no memory of the event.
- Even if he had memory of the event, doubting its authenticity.
I think the film shows that he is not guilty of suppressing information, but that everyone has been guilty of simply missing information.
As the screenplay states at the end of the film:
ROBBY We buried the story in Metro. No folo. Sacha found the clip.
BEN That was you. You were Metro.
ROBBY Yeah, that was me. I’d just
taken over. I don’t remember it at all. But yeah.
The room quiets. Gut
punch. Ben shakes his head.
MARTY Uh, can I say something?
They turn
to him.
MARTY (CONT’D) Sometimes it’s easy to forget that we spend
most of our time stumbling around in the dark. Suddenly a light gets
turned on, and there’s fair share of blame to go around.
(then)
I
can’t speak to what happened before I arrived but all of you have done
some very good reporting here, reporting that I believe is going to
have an immediate and considerable impact on our readers.
(then)
For
me, this kind of story is why we do this.
So many people missed so many signs and they were all somewhat culpable. As Marty says though, they were stumbling in the dark and now they've found the light - and all they can do is report it as best they can.