How about the risk to their business when a multinational corporation is X-raying their cores for backdoors (as one does) and finds the state backdoor, and then decides to no longer do business with the hardware manufacturer because of it—and also publicizes the existence of the backdoor, such that other multinationals pull out as well?

(I say "multinationals" because, presumably, purely-domestic corporations could be compelled by the state to accept the backdoor and say nothing about it.)