No. Attribution of motive is never helpful or appropriate as part of a supposedly-technical discussion. If it were, then maybe someone should also mention Fielding's own interest in enabling insertion of ads by proxies. But no, that's exactly the kind of thing the IETF chair's message was trying to address, for all parties involved. If there's a problem with lobbying and conflicts of interest, that needs to be taken up at an organizational level, not as part of the technical debate.

In any case, whether you think that kind of behavior is appropriate or not is kind of irrelevant. That wasn't the question. The question was what motivated the IETF chair's message. Can anyone deny that the hostility and accusatory tone of a message that has been splattered all over the internet today might be part of that motivation?

"I would be very concerned if the chair of the IETF was seeking to quash discussion of this type."

Is it trying to quash the discussion, or merely move it to an appropriate (and more effective) forum?

"That would only prove there is a serious problem."

Only if you accept Fielding's attribution of motive, which is a bit circular. What if we assume, for the sake of argument, that Fielding himself is the bad actor here? Would this still prove there's a serious problem, or would it be addressing a problem? See how it all depends on which assumptions you start with? That's why allowing stuff like this into a supposedly rational debate is so problematic. Do you think it would be useful for anyone to make assumptions about your agenda*? People need to stick to the facts, not try to paint anybody who disagrees with them as thralls to some evil agenda.

I agree, in fact the author seemed to go out of their way to explain everything.