My understanding is that if there is CSAM already on the ledger then here in the UK running a node is highly likely to make you liable to criminal prosecution.
Running Knots will not remove this pote...
If a country can jail you for a random blob of data on a node you should probably move countries. Hard forking is just asking for an attack vector. You will always be able to embedd csam into the chain. Letting the state define random data as csam is the error.