People who don't see it as a problem should take the time to read one of dozens published papers outlining the dangers and problems it will pose. If they then still don't feel it's a problem, they're encouraged to publish their own research supporting that view.
We can not do this forever if we want a real human outpost there.
On the other hand, our solar system is but one among many and the longer we hesitate in exploring this one the longer it will be before we are able to explore others. TAn excess of caution can become an excuse for inaction. If earth is an oasis in a planetary desert, the way to find other life is not by maintaining extreme caution about disturbing the surrounding sand dunes but by trekking across them in search of other oases.