>= and > are numerical operations, so both sides are interpreted as a number, and null is 0 when treated as a number. That means `null > 0` becomes `0 > 0`, which is false, and `null >= 0` becomes `0 >= 0`, which is true. In contrast, == is a much more general operation that works on numbers as well as objects, strings, and all sorts of other things, so it certainly doesn't make sense to always convert both sides to a number first. I'm certainly happy that `null == 0` is false in JavaScript, and I wouldn't want that changed to be consistent with numerical comparison (which comes up much more rarely than equality checks, at least in my code).
This type of issue isn't unique to JavaScript. In Java, if you have boxed Integers, `==` will do object identity comparison (so two different instances of the same number will compare as not equal), while `>=` etc will unbox them and do numerical comparison, which I think stems from the same issue of equality being more general than numerical comparison.
Also worth noting that it's not always true that `a >= b` means `!(a < b)` in JavaScript. `'a' >= null` and `'a' < null` are both false.