Someone told me because of this location this wall may be weight bearing. The wall is made with regular single 2x4 spaced about 18" apart. House is a 2 story made in 2009.

 

This could very well be load bearing, especially with what looks like a stairway directly to the left.
You should consult a local structural engineer or architect to come out and look at building.
If you really want the pass-through, maybe they can suggest opening up entire wall, placing a header or beam above the opening. They can also detail how header is secured and supported at ends.
In the meantime, I would temporarily support ceiling:

1) Place a 2 x 6 on floor, as close to the cut-out wall as possible (outside of ceiling register)
2) Place a 2 x 6 on ceiling, plumb with floor 2 x 6
3) Wedge (3 or 4) 2 x 6's vertically between the bottom and top plates.

 

So, there is no way to tell from pictures? I asked a contractor and they told me is doesn't seem like it. They said the wall next to the stair case seems like its load bearing.