This is a case where most people are going to naturally take it literally. Most people don't hear someone espouse "write drunk, edit sober" and think "oh i bet that's a metaphor, they hear a justification to drink more. This is actually the first time I've heard someone claim that quip isn't literal, ever. That's because its not formed as metaphorical advice, its formed as a very specific instruction. There's nothing there to indicate that it should be mulled over and tweaked apart for deeper information.