I don't think that liberal democracy has ever really allowed democratic control of foreign policy. Until our capitalist world state starts to crumble all any electoralist communist party can do is advocate for less exploitative domestic policy. Until the US declines its puppets will be manipulated with short strings. Electoral parties, unions, revolutionaries, can effect policy within their borders. The only way to change exploitative foreign policy is for the victims of it to fight back.

The JCP isn't going to take a stand, and potentially lose voters or risk the wrath of the other parties, on principle. The reality is that foreign policy is what voters care about the least. It doesn't effect them directly.

Think about Corbyn, his stance on Israel was correct but it also lead to him getting smeared as anti-semetic. Would the media have found something similarly nonsensical to slander him with? Probably. But its easy to look at that and see something avoidable.