It's quite possible that his ESTA application (although at first automatically approved) didn't match up with the records (which might have not been updated either).
I-94 F: "Have you ever been denied a U.S. visa or entry into the U.S. or had a U.S. visa cancelled? If yes, when? ______________________ where?"[1]
Last year his work visa was at first denied. And only granted after intervention by the Washington University St. Louis.: "Schon vergangenes Jahr hatte das amerikanische Konsulat in München meinen Antrag auf ein Arbeitsvisum zum Zwecke einer Gastprofessur an der Washington University in St. Louis zuerst negativ beschieden und erst nach Protesten der Universität und einer erheblichen Verzögerung, die einen Teil des Semesters nutzlos vergehen ließ, das Visum erteilt."[2]
So possible simple explanation could be:
He assumed his visa was not denied and answered question F with NO, since he got one, but that didn't match up with the a possible record of his denied visa application. So his entry could arguably be denied on formal grounds only. Still bad style on not giving him any clue what went wrong. This would tell more about a bureaucracy state than a looming surveillance state, yet the two are not exclusive to each other.
Quite likely he also would have gotten in with an actual Tourist or Business Visa (B-1/B-2)[3], once approved they are way harder to revoke instead of relying on an over-automated process like Visa-Waiver/ESTA if you would have any unclear answers on an I94.
I-94 F: "Have you ever been denied a U.S. visa or entry into the U.S. or had a U.S. visa cancelled? If yes, when? ______________________ where?"[1]
Last year his work visa was at first denied. And only granted after intervention by the Washington University St. Louis.: "Schon vergangenes Jahr hatte das amerikanische Konsulat in München meinen Antrag auf ein Arbeitsvisum zum Zwecke einer Gastprofessur an der Washington University in St. Louis zuerst negativ beschieden und erst nach Protesten der Universität und einer erheblichen Verzögerung, die einen Teil des Semesters nutzlos vergehen ließ, das Visum erteilt."[2]
So possible simple explanation could be:
He assumed his visa was not denied and answered question F with NO, since he got one, but that didn't match up with the a possible record of his denied visa application. So his entry could arguably be denied on formal grounds only. Still bad style on not giving him any clue what went wrong. This would tell more about a bureaucracy state than a looming surveillance state, yet the two are not exclusive to each other.
Quite likely he also would have gotten in with an actual Tourist or Business Visa (B-1/B-2)[3], once approved they are way harder to revoke instead of relying on an over-automated process like Visa-Waiver/ESTA if you would have any unclear answers on an I94.
[1]http://forms.cbp.gov/pdf/visa_waiver.pdf
[2]http://www.faz.net/aktuell/feuilleton/buecher/autoren/ilija-...
[3]http://travel.state.gov/visa/temp/types/types_1286.html