In all fairness, 2Div, that is not exactly what was said. I first read it the way you seem to have and was going to comment that LDS, Watchtower groups, and Christadelphians are not Christian (the post doesn't mention the word Protestant) groups, then I re-read it.
If it's a non-trinitarian group it isn't Christian in the first place... ;-) The post states "Several nontrinitarian religious groups also oppose infant baptism, including Oneness Pentecostals, Christadelphians, Jehovah’s Witnesses, United Church of God, The Church of Jesus Christ of Latter-day Saints[56] and the Community of Christ."
Not trying to incite anything here, just stating that I read it wrong the first time too..
I'll leave the discussion of whether baptizing an infant does anything more than create a wet baby for another time, other than to state that some guy named Peter mentioned a certain order in Acts 2:38, that being "Repent and be baptized.." Not sure how an infant repents.