Ever since Equestrian magic entered the human world, someone by the name of "Sunlight Sunshine" has written books about it.

In one of these books, there was information about the portal mirror that allowed travel between both dimensions.

And it was this book that gave Sci-Twi an idea: if the sirens could go through and prove they had reformed, maybe the same could be done for Equestria's other troublemakers.

Yup, doesn't sound like a bad idea at all!