by Lawcomic
8.1.2 is not ambiguous. But everyone is playing it absolutely contrary to how the rule is written.If DEFCON is at 4 (and I think currently this is the only level where it would be an issue) and an event improves DEFCON by 2, most people are simply raising it to 5.
However, under the way the rule is written, the DEFCON would not improve at all.
So, there's no ambiguity in the rule per se, but one is created because of the way people are commonly playing it.