Obviously I don't agree, but that's not quite his argument. It's a
little more nuanced than that.
1. The scientific model
should include* a non-physical component of consciousness, but suggests that that non-physical component goes away at death.
2. A non-physical component that goes away at death is infinitely improbable.
3. Therefore the scientific model is wrong and immortality is the only conceivable alternative.
He's trying to get us to agree to 1, which does
not include life after death, so that he can then triumphantly point out the supposed contradiction. The problem he's having is that we
don't agree with 1.
(At least, I don't.)
* "should include" is the exact claim he made at one point, though I'm too lazy to hunt it down.
Which central issue?
There's so many weak links in his chain of reasoning that it's really hard to point to just one and say "there's the flaw." All three of the points I mentioned above are required elements of his argument, so all three could be described as central.
So far, we're stuck on 1, but 3 may be a bigger problem overall. And he doesn't even seem to recognize that 2 doesn't necessarily follow from 1, which is another pretty major problem.