Disabling a relationship via API will not remove the inherited membership

Tested and confirmed the bug on demo.civicrm.org which was using 4.3.x when testing. When disabling the relationship (which provides a membership by inheritance) via the API, the inherited membership is not removed from the secondary contact. I created a membership type (family) with relationship for inheritance (spouse of). I then added a membership to one contact and a relationship (spouse) on another. The inheritance looked fine and I could disable/enable the relationship and the membership is "removed"/"added". But then trying the same thing with the API (using civicrm/ajax/doc) will disable the relationship but the membership is still showing for the secondary contact. I can only assume there is some bug or missing functionality in the API. I will update this if I find anything in the code to suggest why.