CarnalK’s point was that we don’t know their reasons, so we can’t actually say if we agree with them or not. It’s entirely possible, for example, that caretakers in a particular area might be aware that the ecologically sound thing to do is cull an albino deer from the population, but have decided not to out of economic or political considerations. We don’t even know if these restrictions were passed by actual conservationists or ecologists, or if they were fluff legislation made by a politician trying to pimp up his enviromentalist credentials.
That’s really a very simplistic and largely inaccurate understanding of evolution. From an evolutionary stand-point, sterility is a huge problem, for the obvious reasons, but it doesn’t prevent a sterile animal from living a long and healthy life. There are plenty of other conditions (including albinism) that can be a “real” problem, even if it isn’t necessarily a death sentence for the afflicted animal.