The Question is does a power focus add its rating to the magic rating for purposes of the Magic*2 limitation on the force of spirits. The "call on and control" reference in the description could be read either way. It could mean summoning tests, or all aspects of "calling on" a spirit including max force.

Power focus's don't add to magic rating, just dice to the dice pool (SR4)

That depends on which edition he is playing. An important piece of information that he failed to provide. As far as SR4 is concerned, you are correct, of course.