The name makes sense because Aluminium has an -ium suffix like Chromium. There's also no reason for the project name to agree with the US pronunciation of the element.
Well, it makes sense and it doesn't because it makes it sound like this is a 'lightweight' version of the Chromium-based products while the opposite seems to be true. Call it Osmium instead, that's got '-ium' and some weight to it just like this thing.