To be fair, it's unclear whether Linnarsson was saying that brain uploading would never be possible (which is a step too far), or that this company would never people to revive people who paid today using brain-uploading techniques available within the near future (which is quite reasonable).

I fundamentally don't understand those comments.

Like, I get that these guys might be - maybe even probably are! - snake oil salesmen, but what about brain digitization is actually impossible? There are certainly a fixed number of neurotransmitter types, a fixed number of channels, a fixed structure to a particular operating brain, and so on. Anything that exists can be reverse engineered and, in principle, rebuilt.