As I said, unless something is unusual, the user units in your layout would typically be in microns (that's certainly the default, and I've not come across many people changing that default), and hence the area returned by abArea will be in square microns, and so would not need any multiplication.
Even if you wanted it in some other units, what's so difficult about doing the multiplication? It's a programming language after all - all you would need to do is:
and then use abAreaInSquareMetres instead. Or change the abArea code to include the multiplication.
I don't understand why that's a problem for you?