I don't think that's funny or a valid comparison.

Dogs aren't even the same species. It's not immoral to be afraid of them and having PTSD because of negative interactions with a particular predatory canine species is very normal.

Hopefully service robots won't be very far into the future. I don't want to discriminate against blind people. But I really don't think there is a problem with not being okay around a particular set of non-human species (alligators, hornets, lions, coyotes, dogs, bears, mosquitoes, ...)

I don't think it's funny either. I am a black person, and plenty of white people have been traumatized by their experiences (or lack of experiences) with black people. It's also not "immoral" to be afraid of anything, it is uncontrollable.

Don't avoid a direct, clear question by painting it as non-serious.