To be perfectly honest, it's not that risky. It won't be hard for him to get an academic job somewhere if it doesn't work out. This is usually not the case, but

To be perfectly honest, it's not that risky. It won't be hard for him to get an academic job somewhere if it doesn't work out. This is usually not the case, but for someone with his background, finding another academic job won't be difficult if he's willing to work outside of a highly-ranked research university math department (and the probability of being able to get one of those jobs is even good).