It looks like Tony’s extruded the arm and adjusted the position using grabs rotates and scales. Then before he added the hand, he rotated the arm longitudinally so the palm faced down. There appears to be some rotated edges at the elbow area.
Does it matter? Not as much as you’d think. The hands will be much easier to rig when facing palm down, and the slant of the arms helps avoid some of the distortion that might occur when bending a joint too much (since the arms are raised half way, you can raise them to shoulder height or lower them to his sides without much distortion.)
Other than those considerations, matching the background image is a guide, not a blueprint. At some point, you stop modeling the background image and start modeling the model, if you know what I mean. You’ll be doing enough tweaking on the mesh later on to worry about it now.
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