That explains it! The website you refer to is endorsed by the American Battle Monuments Commission (ABMC) but constructed and maintained by a private concern (and very poorly I might add). This unit is one of the myriad of errors contained but I guess it beats nothing (even a broken clock is right twice a day).
As far as his role in the defense, the story was pretty much the same for all concerned. Everyone resisted until it was no longer feasible - or even possible - to do so. Sailors eventually scuttled their ships, airmen eventually destroyed their aircraft, artilleryman eventually spiked their guns, etc., and all joined the the ground troops in the withdrawal which ultimately ended at Corregidor.
His correct service number is 6 735 516. You can use it when you order his deceased file.