Introducing a new species is worrisome, even for a technophile like me, but they are not introducing a new species, but merely sterilized mosquitoes of the same species that is already there. Playing God? That's like saying you play God when you reach for the fly swatter..
They do not know what affect the process will have on the species. Good or bad they have a purpose ( I don't know what I hate them ) or God would not have made them. They also have no clue as to what happens in 2,20,50... years. They is always some other species in place to take the place of one that went away. We may not like the replacement.