If a person has some interesting Github activity (that they can back up) I would certainly discuss it with them. If I'm hiring for a Django developer and the candidate has contributed to the Django core or a related library, that would be a strong signal - but it should not be a requirement. A strong candidate is typically a mixture of good work history, side projects, hobbies and interests, personality and other things that indicate they would be a good fit for your team. How much and in what way depends on the job and the person. Maybe the startup company needs a person who does lots of side projects, builds stuff on their own etc because you need self-starters that don't require lots of hand holding and are ready to take the initiative to learn. On the other hand your 1000-strong engineering subdivision at big corp needs more heads-down 9-5ers who just produce reliable output. Maybe the things you ask a junior dev out of college are different to what you would ask a mid-career developer. There's no one size fits all approach that people seem to be looking for.
Sure, that's why I said "if" - if they don't have a public presence then give them a test.
But frankly I don't really buy that excuse. Those people have time for multiple coding tests but they don't have time for a (small) public project? Ehhh. Not convinced. If you can get away with no portfolio to begin with then you're not going to be inclined to accept coding assignments.
Not everyone has the inclination or time to code outside of work. Many of these people are still very competent developers.