Sure it is, but going to Mars at this point in time is not the best option. How are we going to have a self sufficient colony on Mars without having a viable energy source, for example? We aren't realistically going to set up a Mars colony without first sending lots of robots to prepare for our weak bodies. Bringing each one from Earth is not feasibly either, so you'd want to have a self sufficient (and replicating) robot colony on Mars first. Once we have these and more issues sorted out, it will be worth investing significantly in actually getting the stuff to Mars, but doing it at this point we'd be investing a of of effort in getting there without actually being able to accomplish something once we're there.
The same applies to the moon: what have we done on the moon? Not much. What have we gained out of the moon missions? Plenty of stuff like better rocket engines, heat shields, etc. Was it the technology project that would have gotten us the best return on investment? I don't think so. Was it better than spending the money on e.g fighter planes? Yes (the cost of the JSF project is $1.1 trillion [1], the cost of the Apollo program is about $0.13 trillion in today's dollars [2] [3]).
I did, see two levels up. Note that if your sole goal is to remove Earth as the single point of failure for humans, Mars is probably a good choice. All I'm saying is that at this point doing a mission similar to Apollo, namely flying humans to Mars and back, is not a smart investment (even if your sole goal is to establish a Mars colony, but certainly if you also like to improve conditions on Earth).
It's not a single point. We could alternatively synthesize humans or modify humans to survive apocalyptic conditions. Or build sustainable low orbit colonies. Or transfer our knowledge to artificial intelligent agents. Or simply fix the planet so it doesn't become a point of failure.
He is referring to the inevitable extinction event that will cause humans to be wiped out. The history of the planet suggests that it periodically wipes the slate nearly clean. And while there are human reasons we might get wiped out (war, warming, techno catastrophe) even being ideal stewards will eventually result in the loss of the human race. The only survival option is to not be on planet when the 'bad thing' (what ever it happens to be) happens.
If the extinction event is caused by asteroids, that's not the only option. That doesn't mean that the alternatives wouldn't need spacial technology anyway.
