That's assuming that the thing he wants scaled is a single image that never changed. For something like the game screen you'd need to re-scale it every frame.
Scaling the image every time you draw isn't as slow as you might think. Certainly not as slow as you make it sound :}
Of course, depends a LOT on the size of the image.
Maybe, i'm a bit of a performance paranoid person
And it also depends on how much you want to scale as well
I remember scaling a 24x24 tile to 480x480, 600fps dropped down to ~10