I wouldn't soak it in anything--my guess all that would do is cause the glue to turn loose.

As best I can tell, that bow has no glass or any other backing (selfbow). Stringing it wil be a coin toss--it might hold, it might not. If he does, and wants to shoot it, start by drawing it back a little at a time and listen for cracks and creaks. If it makes a noise, stop and unstring it--it's a wall hanger, and not worth a possible knot on the noggin.

Chad