Carta's
Carta's > Sex
(unless it is based on misinformation or a lack of information).
That's where you fail, though I agree with you. His opinion is based on misinformation: he blames Peter leaving and wants him to stay and help the writing process as he did. Exept he didn't write anything after Still Life, and that was one of the reasons why he left, 'cause he didn't "feel useful to the band" or something along those lines.