I am building a new house and we have the basement poured, the slab poured and the framer is now working on getting the deck installed.

An issue has come up that one solution to the problem could be to add an extra load bearing wall. When we installed the radiant floor pipes we used 2" of foam under the slab, except for the areas where load bearing walls were going, so they would be bearing directly on the load bearing pads.
 
The main question is that since this new load bearing wall was not planned, the area where this wall would need to go has foam underneath it (no pipes). It would be right next to the ICF wall, bearing on the same wall footing (we had 24" footings so there is plenty of extra footing for that wall to sit on.) so it will be sitting on a footing, but with 2" of foam between slab and footing.
Should this be an option? Or not?

Any comments and help will be greatly appreciated.

Depends. Probably not a problem though since the wall will be right over the footing. Foam can support quite a bit of load, unless you used the lowest density EPS available.

What kind of foam did you use under your slab? Do you know what the compressive strength of the foam is? I assume you used either expanded polystyrene (EPS, i.e. styrofoam) or extruded polystyrene (XPS, i.e. DOW blueboard). XPS generally has a higher compressive strength than EPS; although, the compressive strength of Type IX EPS (2# density) is pretty close.

How thick is your slab? What kind of reinforcement was used in the slab? Was rebar placed around the perimeter of the slab? How far off the bottom of the slab was the reinforcement placed? What was the compressive strength of the concrete used for the slab pour? Is the load bearing wall 2x4 or 2x6?

Now, how much actual load is going to be on this load bearing wall?

You should not install a load bearing wall over foam. It has nowhere near the loading capacity of wood. Since there are no pipes under it, just use a saw to cut the floor and foam out right where the wall is going, put the wall right on the concrete, and install some fiberglass or foam in the bottom few inches of the wall if you want to retain the thermal barrier.

Thanks for the response.
We used 2" DOW blueboard and it is a 4", 4000 psi slab, no reinforcement in it. Just fiber mesh in the concrete. The load bearing would be a 2x4. The wall is about 8 ft. long and would be supporting 8 ft of the floor joists and the exterior wall that supports the roof; but I have no idea what the actual load would be.

Aardvarcus, that's what I thought about not bearing on foam, but I wanted to ask and double check. The wall in question right now is just a temporary wall to get the deck on until we have a chance to finish pouring some concrete since it's been too cold. The framer was just wondering if we couldn't just make that a permanent wall so we didn't have to wait on the concrete. But I guess we'll just wait. If we do decide to make it permanent, I think we will rip out the concrete and get the foam out. Thanks for the help.