The club totally said that.
If you don't show in Marseille and you've bought a ticket then it will affect your ability to buy other Europa League tickets.
At time of writing there's 1,702 tickets still available.
I can only imagine that a lot of people have 'expressed an interest' and not taken up the offer.
Blocks C, A, L and M are all sold out bar a few seats.
I'd imagine that there will be a fair few left come Monday's window. Maybe this...