Actually not:

No, well, I understand how a woman can rape a man with a strapon or something like that. But how can she do it in a natural way? If we do not take bandages and other deliberate member damage, does not the man’s sexual organs look like a declaration of intent?

Physical excitement is not equal to consent. For example, he says no to you, and you give him a causal place (say, he can’t push back or resist). The body reacts against the will of its owner, and yes, it is rape. The body of both men and women can show symptoms of excitement even from fear. Therefore - said no (or lack of consent) means no that would not stand there or wet.