No, sorry, I meant the user is lying in this case. Thanks for pointing it out, it wasn't clear on my part.

FF, not unlike many other services, doesn't freeze a specific UTXO, rather they freeze a specific amount (and hand over to LE). They can do this because any coins coming out of their BTC address are marked clean by the chain forensic services. Not unlike what eXch used to be able to do with their aggregate address.