Ah, yes - how interesting the effect of selective memory can sometimes be, can it not? Until you reminded me as above, I'd completely forgotten about that! - whbich presumably says something about its unimportance in the scheme of things. But since you have now drawn our attention to it again, one might argue that the sheer noisiness of such an act of disruption was, like the act itself, so yesterday; it was just about on a level with the young Boulez's noisy and attention-seeking assertion almost half a century earlier that those composers who do not grasp the significance of 12-note serialism were of no use - or indeed the violent protests that took place at the première of Schönberg's D minor string quartet in which Mahler sought to intervene in support of the composer almost half a century before that - or, for that matter, some of the very nasty reviews of a young man almost three quarters of a century before that, following his première as soloist in his E minor piano concerto (I refer here, of course, to Chopin, aged around 20).
All that really matters is that a composer writes just as he/she feels impelled to write. Birtwistle does it; so did George Lloyd. Take Boulez's barb refered to above, which is demonstrably about as meaningful as accusing Mozart of being of no use on account of his lack of understanding of gamelan, or indeed Boulez's own questionable usefulness in the light of his lack of understanding of Vaughan Williams; that kind of noisily empty polemicism may stick in the memory but its inevitable passage into footnote-of-history status illustrates just why Boulez's influence in such matters has ultimately be far less than pernicious, since it has by no means become the accepted norm. Furthermore, time is no respecter of such mental inflexibility and dogmatism, as is obvious from the most casual comparison between today's musical climate and that of the early days of Boulez; the term Darmstadtrophy camoes to mind...