Well, I don't think he has made any effort to clarify what his given name is, so until he does, I think it is perfectly fine for anyone to call him whatever they d*mn well please. I, for one, prefer to use Barry Soetoro.
So you think his “given name” was Soetero, the name of his stepfather whom his mother didn’t meet until after he was born? Interesting logic.
Call him whatever you want. I don’t particularly care. But don’t try to couch it in false logic.
According to records we've seen from his country of citizenship, that does appear to be his legal name.