Complex sentence: In general, he refuses to discuss musical processes and is strongly critical of musicians who form schools and movements (which he calls "clumps") and has on occasion attracted hostility for his attacks on academic commentators, whom he regards as parasitic.
Split into simpler sentences: In general, he refuses to discuss musical processes and is critical of musicians who form schools and movements. He has on occasion attracted hostility for his attacks on academic commentators, whom he regards as parasitic.