"IBM, Google's main rival, questioned the scalability of Google's "surface code" error correction approach"
I believe I questioned the scalability, right here on slashdot, on the discussion around the original surface code paper. The numbers were in the paper showing the error correction could not scale to a lid on BER as the number of qubits and iterations increase.
The text of TFS is underwhelming. "Dropped by half". So you had 10 errors, now you have 5. Your algorithm still doesn't work.
I haven't read the paper yet - I guess I've got to go and do that now just so I can see why it won't work.