[AtlUmpSteve]

Ina an effort to find some reasonable explanation for the ruling, the strange wording this umpire used could have POSSIBLY been a poorly worded attempt to state that the runner had passed the base at the time of the throw despite the OP wording of "had not touched 2nd". IF that were the case, he would be correct in awarding home (although the runner is still subject to an appeal for missing the base if the runner did not return to touch), since runners are awarded bases based on their actual position irrespective of bases actually touched.

However, it doesn't appear that would be the case; to be true, this would need to be a throw behind a runner having passed 2nd, not a throw to retire a runner advancing to 2nd. If it as straight forward as it appears, the words "I protest" should have been used before the next pitch.