I think people are taking offense to this for the wrong reason.
No one is saying boxing can't be modified for street and be very effective for self-defense.
However, if it were already directly related to free fighting, it wouldn't need to be modified.
These things KPM says below indicate that he knows and agrees that modifications need to be made for boxing to be more effective and safer when applied on the street, and there are obviously many more significant and necessary modifications, some of which I described.
In this sense, it is not a martial art, but a ring sport, and not even a single approach to that. But so what? That is not to say you can't use it to knock out an attacker.
And yes, every martial art will have to work with certain vulnerabilities as well, but not for a lack of consideration of possible dangers due to the opponent being bound by ring rules. A martial art, being designed for self-defense, does not need to be modified for the street.