It can be, if it eliminates redundancy in a critical ecospheric niche, because you're then hoping that some virus doesn't evolve to wipe out that last remaining "system" in that niche.
No doubt species extinction CAN be a problem--- but my point was that it is not intrinsically a bad thing, or even if it is intrisically a bad thing, there are times when the negative of species being extinguished is far outweighed by the positive-- the tsete fly being (it seemed to me) an example almost as obvious as rinos.
Wouldn't you both agree the elimination of the tsete fly would be a net benefit to humanity?