--snip--
Now if we (a node) see a system compromise, we require the SHA256(tx) value to be less than 1/1000000 * 256 bit value, we can be relatively confident the issuing wallet has done a certain amount of pow on that tx for it to be issued.
Why?
This is an emergency brake that bitcoin node operators could optionally enable if there was a system wide compromise. It gives bitcoin owners time to issue their own tx with a local PoW to move their funds to a QC safe or uncompromised signature system.
--snip--
Aside from problem i mentioned earlier, it's useless unless majority of node operator enforce this rule. Thief with QC could just broadcast the transaction to node which doesn't enforce this rule.