No details of this claimed 1953 departure to the US are provided that could be corroborated. No journalistic follow-up as to when, where, how a 17-year-old went to the US while Kenya was still a UK colony and Sr. a UK subject with no run-up to independence fueling exchange programs as was the case in 1959.
The romance, marriage and children of Kezia in Kenya from 1955 to 1959 are omitted from the Otula narrative and from a sudden departure for the US his recounting picks up with the marriage to Barry's mom in the US.
The article says this was an “Anglican Christian” school (Note: the students admitted were “exclusively Christian” not Muslim). Out of propriety Christian Otula may have wanted to gloss over the Kezia tribal marriage episode to protect the reputation of President Obama from telling the truth that the US marriage was bigamous.
You are doubtless aware that the top newspapers and news outlets won't go with a big story that they will have to stand behind unless it comes from at least two sources.
Otula was a only hearsay witness to when or whether Senior left Kenya in 1953. Ketzia was an eyewitness and she her children, extended Obama family all affirm Senior as the father of her children that were born in 1959 and 1960 and they did so long before Obama was a celebrity.