[Shrug. Let the bullshit continue!]
That's the corollary. Summoned monsters are magical in their own right. They, along with the wizard provide a necessary part of the power to cross between two worlds through a stable 'hole'.

'Course, that is just the way it works where I come from. Perhaps it's different in whatever world you're from, but, well.

And sure, if you can disprove something that'll happen one month hence.