All I can say is, your FiL needs to be assessed. No-one in their right mind would think that paying an import licence for a pallet-load of cash, was in any way a sane thing to do, OR believable.
I wonder how old he is and what is the background of his 'lodger'.
Remortgaging his home? Taking out loans? At what age? One would think that the bank would become suspicious about him sending money via Western Union which would show on his account or indeed, withdrawing large amounts of cash.
No...sounds like a leg pull but in any case it's his money...let him waste it.
No fool like an old fool.