This makes no sense. We perform trials to gather data, just like any scientist. That's what this is, not strip-mining the sea-floor outright. If the trials proved that this can be done in a responsible way, why not do it? But instead you just want to ban it without gathering any data at all.

We've been mining for quite some time now. Have we ever been able to do it without major negative impact on the environment, at least in the easiest, most practiced of conditions? Mining "in a responsible way" is like "clean coal". It's a euphemism for something that still does a lot of damage but fills some pockets enough to call it whatever they want. The scientists are there just to minimize that damage.