Why is everyone quibbling with him about that. He just wants to express his opinion that the codebase is very bad in a more colorful way than by simply calling it doubleplusbad. Let's just take his word for it and move on.
Aviation. 500 & 1000 ft intervals are very convenient discrete altitude levels for coordinating traffic, and that's probably a key reason why it's held up universally. In meters, the interval will either awkward and hard to communicate numbers or spaced too widely to be efficient.