I was hoping somebody else would field this. I read Attente de dieu some thirty-five years ago, and a couple of scattered pieces of Simone Weil's writings.
It's just too long to remember details, but I do not recall anything that I thought was anti-semitic. At one time she was friends with Sartre and de Beauvoir, when they were all students under Alain, pre-Socratic philosophy I think.
There is no mention of anti-semitism in regard to Weil in either Sartre's or de Beauvoir's work that I can remember.
Perhaps Lewis is taking Weil's rejection of Jewish religion as anti-semitism?
Anyhow, until somebody convinces me otherwise, I don't believe it.
John K. Taber