>extra-terrestrial civilisations will not reckon our resources are particularly valuable
It doesn't make any difference. Don't assume that Jean-Luc Picard will be in charge of the starship that comes visiting - it might be Pol Pot.
In our own history thousands of Indigenous Australians were hunted down and slaughtered simply for someone's amusement, as sport. We can be wiped out for not immediately embracing the great god Thaal, or even just so they can try out their new ray gun.