The distinction between zoosexual and one who engages in beastiality can't be made legally as animals can't consent to sex legally at any time.
For this same reason, a pedophile
can never be legally protected by engaging in sex with a child., as children can not legally choose.
Outside of legal boundaries, the distinction IS made, though it should never be engaged in (as breaking the law is wrong). We all know children can choose, they're just not considered to be concious enough to choose. The same would apply to animals.
The statement that animals only prefer sex within their own species is wrong, as many animals do engage with sex with other animals as well as people. This usually results from sexual repression, deviancy within the species, or being raised apart from their species. This is actually quite similar to a zoophile, which would be a human example of an animal like this.
If the animal initiates sex with the person without violence or coersion through things like food, the animal obviously desires such sexual interaction, and it should be allowed.
It is obviously rape if the animal tries to escape or attack the human, and the human should be punished like any rapist. There's no such thing as an animal masochist
to my knowledge, so that won't work as an excuse.
The most receptive animals to zoophiles will most likely be male animals, as their sex drive can drive them to inseminate and release their sperm into anything possible. Human males can likely identify with this urge, which leads to masturbation and sex with people the male finds unattractive. It could similarly happen to female animals in heat, though I've never observed an example of this.
The zoophile woman would sometimes present herself to her dog, training him to to mount her.