Yes, there are no definite definitions for words. People are free to define them how they want.

For Nokia, Maemo is not the "smartphone" platform, Symbian is that.

Maemo "is an advanced Linux-based operating system designed to run on high-end Nokia mobile computers" (as said in maemo.nokia.com).

Reporters naturally write whatever they happen to come up with, but if somebody wants to write like Nokia wants to position them, then smartphones and mobile computers is currently a good way to go.