That is a very strange article. The headline is “How Boris Johnson Sabotaged Ukraine Russia Peace Deal In April” and the bulk of it is about how a former US National Security Council officer didn’t say that.
Frankly the NYT one seems a lot more convincing to me. That addition to the security guarantee clause is obviously completely unworkable.
We thought we were the ones domesticating grass when we invented agriculture, but the grass isn’t the one that changed how it lives