Without that contemporary context, the quote means nothing.
"Mill supported laissez-faire but with social reforms like redistribution of wealth, shorter working days, and regulation of monopolies. Mill was ahead of his time in advocating the development of labor unions and farm cooperatives... Today (John Stuart Mill) would be called a "moderate conservative" due to his support of some government controls over the economy and because his harm principle, popular among liberals and libertarians, often leads to results that directly contradict social conservatism."
So yes, he thought conservatives were stupid people.