I do not see whats immoral about cloning an extinct animal, i dont even see what's immoral about cloning in the first place. Can i explain why? Nope. I just dont see the immorality. The whole question depends on faith and believes.
From an evolutionary point of view, the sugestion that we would oppose natural selection is just bogus. We were naturally selected too, when we chose to resurrect a extinct animal, doesnt that count as a form of natural selection? And as someone stated here, natural selection is all about probabilities. There's no real driving force, only probabilities that seem to form complex outcomings.
From a theological point of view, i do not see any problem neither. If there is a god, and he 'gave' us the gift of manipulating genes, and cloning long gone animals, why would he rather not have us do it? Then you have the bible too, but somewhere i dont believe that it is written there that cloning is playing god, and even if it would, allways keep in mind that the bible is only an interpretation. Further, blindly believing what other preachers say is not wrong, because you have to make up for yourself what you believe in. Do as Christ, think for yourself and resist the ones who want to impose their ideas and dogma's. Somewhere i think his message got lost. Nowadays everybody is restricted by taboo's, very often imposed by the church that on the adverse should bring out that message of Jesus.
Anyway, i think i'm ranting too much. And maybe i'm imposing my own ideas right now. Take all this with a couple of salt, and do the same with everything.