Forgive me if this is a mis-reading on either part (and if it is, any clarification is welcome!), but from the point of view of a living breathing music theorist I find it odd that Mark should categorise Tim F's position as the objectivist-formalist one. On a scale of subjectivism--objectivism in music theory I've always felt Tim to be on the (good) far reaches of subjectivism. For most of the last 100 years music theory has been extremely, dogmatically, formalist, and it's only in the last 20 years or so that the idea of a listening subject has even been admitted - and that was to bitter debate that still rumbles on. I'm not advocating a turn to formalist approaches to music at all, but I am suggesting that there is a well established discipline (that even the most subjectivist academic acknowledges and deliberately draws upon) of studying musical 'objects' as distinct in themselves. I don't agree with this positivism, but the techniques developed by it are legitimate and valuable when turned to more productive, flexible ends.
Although actual musical meaning (this piece means 'homophobia is bad'/'Tamil terrorists are good', etc.) is impossible, in the sense of direct correlation between music and real life, meaningful (semiotic, etc) structures aren't difficult to draw out in music, and when sensibly applied can be used to speculate on why certain music elicits certain reactions. The whole MIA thing encapsulates this: taking her music and her personal pronouncements at face value (whether you like the purely sensual feel of the music or not), it's difficult to sympathise much with her; but when the music is prodded, just enough, it quickly undermines any attempt to project a consistent, coherent political message onto MIA and her words/actions. What you are left with are a bunch of jumbled up slogans, riffs, cliches, hooks and images. It's from this jumble that people are able to project their own convictions of what her music is actually about. (One legitimate projection is that this is a cheap trick, a po-mo cliche, but that's not a criticism that is often floated.) It is possible, of course, to reject a close reading of the music when forming (and defending) a detailed opinion of MIA, but that would be to reject great swathes of theory and method that can be enlisted to assist in forming that opinion, which would, I believe, be thus incomplete.
Side note - no, as an academic you don't need to enjoy the music that you study: it is, on the whole, an object of professional interest. But on the other hand, if you want to do anything worthwhile with it, you have to have some feeling for it, and be prepared to spend a lot of time with it. For the sake of personal sanity, 'pure' enjoyment certainly helps!