It's not all necessarily to see your code & best work - it's also a tactic to gauge this person's participation in the open source community, their contribution

It's not all necessarily to see your code & best work - it's also a tactic to gauge this person's participation in the open source community, their contributions, and passion for programming outside of the 9-5. These intangibles are generally a bigger deal to startups versus large companies, and therefore a more useful indicator.