from the article:
“The U.S. Embassy told Grant her son was indeed a citizen because Grant was a citizen.”
She is claiming he is a citizen because “someone” said he was.
Lots of poetic license in her description. Fact is he might have been eligible (with this snapshot of possible info) to apply for US citizenship, but he (or she, on his behalf) never did. The law is VERY clear on this, and no verbal statements have any bearing on citizenship.
This guy is a British citizen.
Gee, he needs to contact Ted Cruz and find out how he managed US Citizenship.