GitHub doesn’t sell product in the same way as your examples. They are a service provider. I’d say different dynamics come in with services (hosting content, providing and managing infrastructure, providing support and maybe even consulting) vs products.

Also for people who draw comparison with discrimination against individuals: Companies, agencies and organizations aren’t “discriminated” against in the same sense as individuals. I am not aware of any legislation where it’s considered wrongly discriminatory to decline B2B contracts.