Sorry... I should have been clearer. You're correct, and it is indeed why Occam's razor correctly applied would rule out the alien theory. What I meant specifically, was that its syntax is more complex, but its ontology is simpler as you describe. In other words it's the explaining part that's more complex, so it seems more complex on the surface. So if you asked the average person on the street which theory was easier to understand, I'm guessing most would say the alien theory. So when you use a description like "simpler" as the author did, you can be confused as to what is "simpler".

There's been a lot written on this subject that's hard to do justice here: http://plato.stanford.edu/entries/simplicity/