Calling this a "manifesto" is mostly laziness. It is not actually a manifesto. It is a call to dialog. It is a memo that identifies and describes a perceived problem and thoughtfully follows through with some reasonable suggestions for what could be done about it.

While one can tolerate people referring to it as a manifesto for the sake of clarity, since his name is not common knowledge and there is no other catchy title associated with it, it's not reasonable to use that language to imply that what was written is actually a manifesto by the dictionary definition of the word.

A manifesto is a published verbal declaration of the intentions, motives, or views of the issuer, be it an individual, group, political party or government.

That is quite clearly not what the author's piece actually is.

And here I was thinking that I was being all moderate by not calling it a "screed" or a "rant".

Not like you gave me much to work with. It was a single sentence of bland sarcasm.