Nobody went along with it. The likely explanation for the article is the following. Beecher originally submitted an article to the journal that did not contain these sentences concerning additives. The article was reviewed by Meselson after it was reviewed by the FBI and allowed to go out.
Meselson then persuaded Beecher to add these comments. The FBI did NOT re-review the altered article.
Then the $hit hit the fan. Suddenly Beecher’s article became headline news. The FBI had to react. They reacted by issuing a wishy-washy, meaningless statement covering everyone’s butts. And they gagged Beecher from further comment.
What was that "wishy-washy, meaningless statement"? Do you have a reference?