I've read a few commentaries on Simone Weil's thought and they all uniformly consider her attachment to Marxist thought to be at best naive. From her misadventures with Spanish anarchists and her involvement of the proletariat in factories, farms and vineyards of France.
This seems to stem from their impatience with her mixing with such a low class of people who simply could not understand her on the intellectual plane that she most freely lived, thought and felt in. (Apparently she bored farmhands with her disquisitions on the Upanishads and on Plato). And not, given that they are mainly preoccupied by her self-confessed 'possession' by Christ, the general sense that Marxism, by its critique of religion is generally thought to be atheistic and hence diametrically opposite to Christianity, upon whose threshold - they say - she remained.
This doesn't mean that she was incapable of criticising Marxism herself. She accused it, or rather considered to have fallen prey to a novel form of polity in the 20C, that of 'bureaucratic oppression' by a 'bureaucratic caste' which she claimed that Marx hadn't foreseen.
Yet it seems to me that her so-called naivety is simply the mistakes that any pioneering activist-thinker can be accused of. They make the first mistakes and the first advances from which later thinkers and activists learn from and so who do not make the same mistakes (or at least, make them differently).
After all, we now have political philosophers interested in the question of labour and anthropologists who investigate the lived experience of the poor, the disadvantaged and the destitute in their many dimensions and this with institutional support whilst she had none. After all, she explained herself to others by saying that although that there were many Marxists interested in the problem of labour, few, including she said that of Lenin, had stepped inside a factory to discover for themselves what exactly were the lived conditions that these proletarian workers experienced. This, she determined to find for herself. For her, experience counted for something.
To me, this seems completely of a piece with her interest in Christ who sat down with sinners, prostitutes, tax collectors and other marginal figures in society. To understand one, is to understand the other; and likewise, conversely.
Q. So why the impatience shown by these commentators of her profoundly-felt Marxist missionary work, so to speak? This 'Marxist missionary work', more broadly speaking, has also been noted by Martin Luthor King, who during the anti-communism progroms of mid to late 20C USA pointed out that Christianity could learn a great deal from the zeal for social reform, if not revolution, that the Marxists exemplified.
In his memoir of 1958, he wrote that he was sympathetic towards Marx's critique of Capitalism, finding the 'gulf between superfluous wealth and abject poverty' that existed in the United States morally wrong; and in his later book, Where do we go from here?, he decried the morbid fear that the United States had of Communism, arguing that it prevented people from adopting a 'revolutionary spirit ... and declaring eternal opposition to poverty, racism and militarism'.