I don't think those are spokes behind Colt and Number One. Notice there are two "spokes", one above each character but we know that in the wide shots the ceiling ring has only 6 spokes. I believe what you see above their heads are trim moulding near the top of the set's wall. The spacing is too tight to be spokes from the ceiling ring. I've included a visual to show where the characters are and where the strut would be and why they are not visible in the shot you linked to. Now, whether they actually built 6 struts I cannot say. It's very possible that they only built 4 and deliberately shot around the missing 2 struts for whatever reasons.