I hate to say it, but I agree. My most annoying collegue is the most dependable, knowledgable person I know. Once you navigate his fuckedupness he is quite a joy to work with, but god forbid I ever socialize with him, it is a nightmare.
Coffee with a co-worker isn't socializing. In many cases it's just an extension of work.
I'm pretty sure that "grab a coffee with" is a smartass way of saying socializing.
Grabbing a coffee, while talking about work isn't worthwhile mentioning.
Why would someone say "I have one simple rule: I don’t want to work with people whom I wouldn’t [work with]?" That's a meaningless tautology. You also don't need to know someone's life plans and literature preferences if you're just working with them.