: ß is the 233rd Unicode character.
I love your explanation, even though the game itself did not use Unicode, and Bungie was probably not even aware of Unicode at that time. The character "ß" is 167 in the Mac OS Roman character set, which is the encoding used by the game Marathon. Still, it's perfectly logical to speculate that the ship Marathon would be using Unicode; it's more likely than assuming the already-obsolete Mac encoding would make a comeback in 700 years.
FYI, Mac Roman had a handful of Greek characters, but no real beta symbol, so the German letter was often used as a substitute in Mac version strings and such.