Parent is not speaking about cache (L1/L2/L3/...), but about main memory (RAM) of which 16GB would be permanently integrated into the CPU - this would be L1 RAM and of the rest, L2 RAM which would be outside of CPU.
I’m not exactly sure why they mentioned it, but in their defense—it is all fundamentally volatile storage, just used differently. Memory of course has a special magical meaning to operating systems, but hypothetically it might make sense to mark L3 cache as memory, and maybe… treat DRAM as swap? Hypothetically!
It wouldn’t be a cache anymore in that case. The hardware thing is named after the typical job we have for it, but if we want to play with the idea of changing how things are used the names might not line up perfectly anymore.
