Ideally from a business setting
Order new coffee and give the grounds away to someone who can make espresso from it. You could offer it as a gift to guests or others.
If you do end up using it for the guests, make sure you indicate the problem. If possible, try one of the methods below yourself first.
On actually using the coffee
I wouldn't be too worried about the grounds coming through the mesh, they almost certainly will. This is easily solved by pouring your coffee through a paper filter. I know don't normally do that for French press, but in this case it seems sensible to do so.
I'd be more worried about extraction time and taste. When I make French press, I grind as fine as possible without it becoming to bitter, with a consistent time the particles are still larger than holes in the mesh.
Since the coffee is already ground, you can play with two factors: time and dose. You probably want to use less time then you're used to. The dose is difficult, if you use too little coffee, you won't get a full body. If you use too much, it will taste very bitter.
Alternatively, you can try to make turkish-coffee in a pan. The espresso grounds will be alright, but a bit on the big size for that.