The villain is missing the elephant in the room:
People can get VERY creative with magic. It breaks the rules of reality, and having it means people can be just as dangerous as a gun, bomb, or even nukes.
Autonomous summons that can burn anything they touch. A dragon that can destroy cars. Brainwashing an entire party of people to not only be willing slaves, but to also look like a specific person. Splitting a person into two, leaving both intact as viable and complete people, capable of living and spreading any "curse" that the person had for the second person. Turning to stone to extend your life. This is only the START of what can be done with magic, only what we've seen.
The only way for a transition to having more magic in the world be safe would be to create a universal change in magic that would drastically increase humanity's natural resistance to magic all at once, before or as the change happened.
I'm betting magic could make a savvy person immune to bullets too.