Story

I watched the video from IBM and they explicitly mention that they store 8 different values per cell, i.e. 3 bits.
So this has nothing to do with ternary data.
The comparison with 2-bits comes probably from the fact that previously it was only possible to store 2-bits per cell in PCM (phase change memory).

For example with flash memory there is SLC where each cell stores 1 bit and MLC where more bits are stored, in particular they also have TLC with 3-bits per cell. MLC for flash makes the storage denser and cheaper, but also increases wear.