And in the same way, Hawking's quote presented a higher meaning than what is literally there. He didn't literally mean that there will be nomadic alien races out to take over our planet. He only used that as one possible example of how contact with a more advance civilization might be a bad idea just like I used rapists as one possible example of how releasing all prisoners in one day is a bad idea.
I accept you have a point in that respect, and maybe I was unfair to criticise Hawking, especially as it was one quote lifted from a whole series.
Yes, there may be other dangers from aliens apart from just the prospect of war.
But I still hold the opinion, as others clearly do, that it just seems staggeringly unlikely that any aliens would
need to come to the Earth for selfish reasons, when they could almost certainly find whatever they need much closer to wherever they come from.
I would like to think that if we found life today on one of the planets or moons in our own solar system, we already have the awareness to treat it with the utmost care and respect. I may be naive in that but I really do think that given a "fresh" planet with life we would make our best effort to look after it.
I'm also hopeful that we will develop the technology and social attitudes necessary to clean up our own planet long before we have the technology to travel to distant stars. If we don't, we'll almost certainly destroy ourselves long before we have inter-stella technology. I think it is likely the same scenario would apply to any alien species.