Later Mīmāṃsakas on arthabhāvanā

I have already mentioned Bhaṭṭa Śaṅkara's interpretation of artha in arthabhāvanā as “puruṣa”. It is such a surprising interpretation, that I would like to know how he came to that. I never read it in any other author and Bhaṭṭa Śaṅkara does not explain in detail why it has to be like that. He rather presents it as if it were self-evident, a hint to the fact that it was an interpretation well-spread in his milieu? Or does the cursory reference refer to the minor importance of the etymological interpretation? In fact, other Mīmāṃsakas just do not bother in etymologically explain the meaning of arthabhāvanā (unlike they do with śabdabhāvanā). So Rāmānujācārya and Āpadeva, the author of Mīmāṃsānyāyaprakāśa. In his excellent translation of this work, Franklyn Edgerton uses “end-efficient-force” for arthabhāvanā, but he does not explain how he came to that translation.