crablab, if your favoured instructor hasn't flown the TB-10 before (which I assume is the group aeroplane), then he will need to receive familiarisation from someone familiar with the aircraft.
The fact that he has umpteen thousand hours from the airlines is utterly irrelevant - if he's a half-way decent instructor he should know the Part-FCL requirements for variant familiarisation and/or differences training. Self-briefed familiarisation, whether it's even lawful (no doubt some barrack room lawyer will disagree) is not a particularly sensible course of action for an instructor to take.