BD is owned by LH and 99% of their flights do not involve US O/D! So statistically they would be correct, just because they are wrong for your specific trip and query is no reason to be so militant about it. Also every other aspect of airline ticketing is equally wrong at times, with wrong fares, fare rules, tax computation and ticket issuance being closer to the norm than the exception, so no particular reason to be up in arms over this very minor matter. Close counts with airline tickets, just as with horseshoes.

It would have been better if MSC rules had been drafted by IATA to be compatible with the existing US DOT rules, but obviously enough non-US airlines voted otherwise to create the current MSC -- which is a huge improvement over the pre-302 situation. Give it a year and it will settle down to be routine, its less than 6 months so far.