^ The original casting choices were Viggo Mortensen (America/ Danish), Daniel Day-Lewis (English born, Irish passport holder) and then Neeson (Irish/UK citizenship). The character originally seemed to have a French name and wavering Irish-Enghlish accent Then there was the decoy Japanese Ra's. I don't think there was ever any intent to have him be Arabic.
On a practical level, casting an Arabic-looking actor as "Ducard" would have given away the whole "decoy Ra's al Ghul" twist. I suspect that casting a European actor as the real Ra's was more a case of deliberate misdirection than political correctness.