Doesn't look like ESTA is the issue:<p>> On EU side if airport personnel told you it's their flag, not the ESTA that is the issue.<p>> How frustrating. Whatever system the airlines are using it throws up erroneous flags, often.
For anyone unfamiliar, the reason the airline would've denied him boarding if they even thought there was an issue with ESTA is because airlines are responsible for bearing the cost of his return flight if he is denied entry in the US. Shame, really, since it seems like there's a decent possibility that had he actually made it to the US border he would have been allowed to enter.<p>The whole system is somewhat archaic and outdated.