I recall reading that he considered himself a Marxist, and he does appear to support revolutionary approach to social change in his books. While Ministry for the Future isn't perfect, it did some economic analysis showing that capitalism is fundamentally at odds with having a livable future. The whole thesis of the book is that capitalism needs to be abolished, and the book also doesn't shy away from saying that violence will be necessary to do so. It also talks positively about USSR saying that it had the right idea all along.