Well, I guess it's just reading the comment two entirely different ways. The way I read it, it sounds like someone who loves programming, not being able to imagine how you would never want to program outside work–not 24 hours a day, but never at all. You know, for the fun of it.

You make it sound like the guy is your boss, making it a requirement for employment that people do programming they don't want to do outside work hours.

The guy said "probably" and "is how I look at it", but that wasn't enough–the words are still treated like he'd said "definitely" and "I'd make this a legal requirement" or something. Ah anyway.

Things don't have to be legal requirements to effectively be requirements. I'd hate to be considered not fit for tech by my coworkers, my boss, a potential employer, ... because of how I like to spend my free time, and if that sentiment is common it is a problem for people not fitting that expectation. Which I think is be bad, even if I personally would benefit from it. And you see people push others out with arguments like this, it's not a theoretical thing. (I'm not saying the original commenter is doing so, but explaining why I read the comment as negatively as I did)