In that case, no worries and no hard e-feelings.

By the letter of the AC law, it appears they could charge you a reservation fee if one didn't want to select an option (BA) that didn't yield status miles. If you input a flight to & from JNB the seemingly-obvious option of using LH isn't offered at all. There must be some behind-the-scenes alliance complications if AC finds it preferable to code-share with BA in favour of their Star partners.