Also, Tim had a personal relationship with the Peraltas and, after everything that has happened, he just wanted to make sure that the Mexico JV was solidified and then he needed a break to be with his family. It has been a tough two years for him, no doubt about it.
Remember, he owns quite a bit of stock and if the Mexican JV flies, he will be set for life.
And, finally, once the JV was set up, perhaps they want to cut the costs on his CTO salary.