And no accident has happen yet so there is no case law which just shows you the risk you are taking
Crack on take your PPL mate up as PIC. And be done with it.
Actually, there have been accidents, but as you say, no case law.
The example I have in mind ( a real one) was of a pilot out of currency flying as handling pilot with a mate. He screwed up on landing and wrote the aircraft off.
The PIC, very generously, said he had been the handling pilot. Fortunately there were only minor injuries but, due to the generosity of the PIC, the insurance paid out.
As you say "Crack on take your PPL mate up as PIC. And be done with it."