Well, of course you're technically correct, Whopity.
A UK FRTOL issued after 17 September 2012, does not expire, but it is not valid unless the holder has language proficiency in English at Level 6, or at Level 4 or 5 that has not expired.
Since the FE can only confirm Level 6, what I really meant was that he/she should fill that in, so that the FRTOL included in the licence will remain valid.