DFC,
Illegal public transport is not a good start to a career as a commercial pilot.
Is it public transport flight if the pilot paying the passenger? The ANO says it is public transport if the cash is flowing in the other direction...unless I've missed something.
I will always check and sign the logbook entry of the pilot doing a check for any reason. They will be PUT unless it is a Skill test or LPC when it is P1/S provided they pass and PUT if not (even if they have a valid licence at the time!).
Surely PU/T is only relevant if you are actually being trained, as there is no recognised rating or qualification (neither a revalidation or type checkout) for flying to le-took then there can be no instruction recognised by the CAA and thus no PU/T. If that is the case, then the flight was either unloggable (P1 for the instructor) or P1 for Nuclear Weapon.
If the student does not like the idea then they are not the type of person you want flying your aircraft.
What's this got to do with a chap's character?