It seems you were the one who completely failed to understand the article. Your first point implies you think the author was talking about QUIC in that section, when instead the author was merely using NAT as an example of packet inspection to provide context to the topic. Your second point is in fact exactly the point of the entire article, which itself is a commentary on the decision making process and factors in that process that IETF is presently using to decide exactly how much to "break" the protocols, and moreover on the observation that many people in the IETF do not consider this to be "breaking" at all. Your third point is a commentary on the utility of the bit itself, which is not really the focus of the article anyway.
You claim:
"IMO the article completely fails to describe the actual issue."
You claim: "IMO the article completely fails to describe the actual issue."
How so?