Thanks Echobeat and Great Argus for your explanations,
I stand corrected that presentation animals are free not to go for demonstrations.
I disagree with your definition that their off-show accomodation is good. I saw some of these places, and could compare them with breeding exhibits of the same species in the same zoo. And they were relatively small and bare.
Your issue over 'not tame' is purely rhetorical. They are tame compared to other zoo animals of this species. That they can scratch or bite - many dogs, cats and horses do the same.
The main core of my criticism is they are isolated from other individuals of the species and cannot behave fully normally (even if many species are solitary and meet only occassionally - they still don't reproduce by budding). So my criticism still stands.
I also think it is better call them presentation animals, and not to use the word animal ambassador, because it is marketing euphemism. A tame serval did not attend a diplomacy school, does not wear suit and tie and is not knowledgeable in international politics. Neither is a beautiful cactus in Safari Park called an ambassador cactus, although it shows exotic plant life to Californians. Call spade a spade, and call a serval used for presentations a presentation animal.
Actually, a zoo 40 years ago had no need of special so-called presentation animals or animal presentations. Later zoos fould that animals live better if they can keep distance from people and breed better if they are not disturbed or humanized too much. This led to a zoo of 20 years ago, with large exhibits where animals cannot be seen closely, are free to rest, and people can no longer interact with them. This in turn led to producing a subset of animals which are forced to interact with people and are presentation animals. Then perhaps, it is time to swing a pendulum back a little, and have the same set of rules what is good welfare for a presentation animal and a breeding animal.