I made one of the first comments, and it's almost exactly like what @Thucydides wrote 7 hours later. It was't rude, bigoted, abusive, unfriendly or unkind, and was certainly "needed".
Comments are for asking for clarification or suggesting improvements.
Comments are not for posting answers.
Comments are second-class (or even third-class) citizens on Stack Exchange, and can be deleted at almost any time for almost any reason, with or without diamond moderator involvement.
Just because a later comment hasn't been deleted doesn't make the original deletion inappropriate.
Compare What are the criteria for comment deletion? and stackoverflow comment etiquette and How do comments work? (for the latter, particularly the sections on Who can delete comments? and When should comments be deleted?)
I'm not certain but I'm pretty sure I flagged the comment in question as being too much of answer to be left as a comment, or in fact to be left as a one liner. It was good material that deserved proper elaboration. My opinion was subsequently upheld at moderation.