It is terrifying that anyone would ever think that was a good idea, let alone someone respected enough to have 128K Twitter followers. How much more plainly can you say "we're not interested in anyone who wants to spend evenings and weekends with friends and family"?
First of all, having a github profile doesn't mean you "don't want to spend evenings with friends and family". It means you spent some amount of time doing stuff on github. Ignoring people who get paid to write code that is on github (most open source projects are mirrored there now, so there are quite a few), all it means is that coding is one of your hobbies.
Aside from quality time with your family, perhaps you spend a few hours a week playing the guitar, or reading epic fantasy novels, or playing soccer, or perhaps you spend some of that time hacking for fun. Some very good hackers are exactly so good because they love hacking on software so much. Not all - some just want to forget code outside of work, that's cool too - but certainly some. More than the opposite, in my experience.
Again, I see your point - to just categorically reject people without a github profile is both insane and immoral (insane, because you are going to lose out on a lot of talent; immoral, because it sends a message that unpaid work is necessary).
But I would say that a github profile is a positive. Aside from showing an honest love of hacking, it also provides code samples that you as a possible employer can just look at.
Also, I prefer Hg/BitBucket for personal code anyway.
Github (or equivalent) presupposes that you've done some coding that is (1) worth sharing with the public (2) organized enough.
A lot of "learning code" is going to look like crap - the first few thousand lines of code you write when you're learning a new language, a new problem domain, or (!) both at the same time. The fact that it isn't useful for public viewing doesn't make it useless - it was an important part of the learning process. But sharing it with prospective employers is unlikely to be valuable.