How can you form this whole entire discussion around Leiby and ignore what happened to R’ Abuchazeira? If you are going to talk about emunah and whether it was up to Hashem or a human being then you have to speak about both occurrences when stating your POV and facts.
As far as the AMI article, just as you would look up the facts in the Torah, Gemorah, etc., you need to look up the facts before you speak about it. Hearing an overheated argument is not a good enough source to “bad mouth” the magazine. It was your responsibility to first read the article yourself to see if indeed the author came to the same conclusion that these bochurim were discussing or whether they misjudged or came to their own conclusion.
The second step would have been to call or write both the author and the magazine and see if they could correct the issue at hand. In the event that they refuse or ignore you, then it would be permissible to bring it to the attention of the public. Being motzei shem ra on the author and the magazine does not make you a tzadik even though you think you are right in your opinion of trying to protect the masses.