No, it is very clear even with the full context that at this point in the article they are referring to the delay of the book being published. The very next sentence states that there were multiple such examples of suppression over his career, indicating that "this act" was a specific one in a sequence of many.
The act is the act of suppression, which they were involved in. They did not participate in the delay portion of the suppression, nor does it say they did.
It's not "the act" it's "this act" which they were not involved in. The article says they were involved in the delay, which is innaccurate. They may not have meant to say that, but that's what it says.
