Isn't it true, that with whatever
gauge strings he's got, that to get the thing up to pitch with the bridge at a certain position is going to require a certain tension,
and no other tension? IOW, it is that stiff because that's the stiffness required to get the strings up to pitch. If you want it less stiff, then it seems to me you need lighter strings.
Unless I'm missing something, which is always possible, it's happened many times before.