No, I am saying that everyone with an interest has a right to have that interest heard, The "moaners", as you call them, have just as much right to have their interest heard as those who want to plonk a concrete tidal lagoon in Swansea Bay. And yes, it IS up to those who want to alter the state of dynamic equilibrium in Swansea Bay to prove that any alteration will not have a significant detrimental effect on the area.
It is up to the decision makers to make the final decision based on all the evidence put before them - but the onus is on the tidal lagoon developers to make their case.