I think we're agreeing more than we think we are.
I've wondered about what having an extended lifespan would actually mean for people's perspective. Would people suddenly be more concerned about climate change, for example? Population control? Doubtful... Would they contribute less to their 401ks? Probably... Making a species designed for short term thinking into a long-lived species, without changing anything else, probably won't affect the typical individual's behavior much. But I digress.
The more I think about that article, the more I think the premise is stupidly wrong -- *unless* some super-xenophobic subspecies creates Von Neumann Berskerers and turns them loose. That would be a problem. But it wouldn't be any more risk to our long term existence than staying put here on Earth, I don't think. Some day, sooner than later probably, somebody's going to invent a horribly deadly *thing* and let it loose to kill us all.