I think Mayt can handle himself, it is not like Sin and Virtue are both S Class wizards. They haven't even hit the bottom of the barrel with their magic yet! They are just handling the basics at the moment, but if you feel like James should enter, there is no stopping you.
Edit: Oh whoops! Sorry, I thought Mayt was much more powerful as I assumed him being an S Class Wizard made him super strong with his magic and combat skills. I'm sorry that I made them more powerful than they had to be, I just wanted Mayt to realize the actual potential they could have after beating them with ease. So yeah, James can help, definitely to even the score. Sorry again Burthstone.