No, in context "this suppression" is clearly referring to the disruption of the novel's genesis and the sending of its author into exile performed by the dictators in that period prior to 1946. The dictators are the censors and exilers being referenced in the next sentence.
It would have been easy to say that those actions were part of a broader suppression, or even just aiding in suppression with no qualifier, but specifying "this" makes it unambiguous that they are still talking about the same thing.
I think if you take the full article as context, where they mention specific incidents in the 50's onwards, the context is not the period prior to 1946. I think it's just this specific paragraph that's clumsily worded.
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.
It would have been easy to say that those actions were part of a broader suppression, or even just aiding in suppression with no qualifier, but specifying "this" makes it unambiguous that they are still talking about the same thing.