Well looking at the Rahtz book, and the fact that an I/A settlement was on the top, and of course the two bodies of the supposed monks in the rock cut graves; the sequence of settlement could be read as pagan shrine/roman temple/christian, very similar to other hill top sites in Somerset.
So a maze can't be ruled out, though whether mazes went that far back into history I don't know..spirally path up the Tor maybe equals easier way for pack animals to take stuff up there?