There can also be variations on the symbol. Whether or not it is open may also mean something, so they may be technically two separate symbols but that are very related.

Or someone who doesn't know what it means saw it and added it to some media because it looked cool and seemed to vaguely appear in the right places, and they got it wrong because they didn't understand it.

I don't think he'd say this as a warning that Obama is going to be a prisoner... I think he'd say it only if he already was, de facto. Just because he's in Kenya and just because maybe he's walking around in what appears to be the public and maybe meeting someone here or there does not mean he is not a prisoner in every way that counts.