It didn't take long for Arnold to get an army of fire giants. Hell, even dragons would have a tough time dealing with the walking hell he had just resurrected from death. With more than a million giants backing him up, Odin thought it was the best time to recall his forces.
Odin did not recall the Valkyries or Valhallan warriors because he wanted to make sure that no one would cause trouble in his plans. While the council back in Asgard was against this move and had started seeing Arnold as a threat more than anything else, Odin trusted him.
Not because Arnold was someone worthy of his trust. But because Shiva had told him to trust the newly consecrated half god and Odin trusted Shiva more than he trusted himself. Thus he readily spent every ounce of power he had to help the man.
