Hi Halifax,
No it wouldn’t be a concern for me. Quilting foam is often used in a cover to modify the surface feel of the mattress, to help the mattress keep its shape, and is a preference for many people vs sleeping directly on latex. If the polyfoam quilting layer is “in the range” of around an inch or so then it wouldn’t have an effect on the durability of the mattress and the quilting will also pre-compress the material and increase it’s durability.
Once a quilting layer is 2" or more then I would want to make sure the density of the quilting foam was good quality because it could begin to affect durability but this wouldn’t be a concern in thinner quilting layers. There is more about the effects of quilting materials in post #12 here.
When you have a high quality manufacturer like Fox it would be very unlikely that they would design a mattress that has any obvious weak links in its construction and this is no exception :).
Phoenix