It's just regular unreadable code. ~ and - are both prefix operators: bitwise complement and negation, respectively. With two's-complement arithmetic, "complement then negate" adds one while "negate then complement" subtracts one.

I got that feeling again when I was trying to learn 6502 assembly.

Amusingly at least in gcc

#\\ this appears legal

Raymond Chen rants about other developers doing stupid things - his job is basically to help them get stuff done in 'the right way' from what I can tell, so he finds a lot of weirdness like this.

My impression is that this is a parody of something ridiculous he found.

Sometimes I can't tell if people are being serious about their objections to this or if they are willingly oblivious.

Indeed. It's more interesting that an explanation (top comment) was posted one hour before this objection to the "feature."