I have a sense (perhaps unfounded) that it's difficult for Chinese tech companies to make inroads outside of China. This is because of the Chinese government's role as a kingmaker within its own tech industry, and because of concerns of IP theft, surveillance, and state-backed hacking from the Chinese government. Big firms outside of China do not trust Chinese software firms with their data. As a big time software company in China, you can only really sell to Chinese buyers, with a few rare exceptions.

On the other hand, a US company can operate essentially anywhere but China. Maybe he thought he had a better shot on his own merits outside China. Maybe he didn't want to get in bed with the party, or maybe he was just a guy who was enamored of the dream that was Silicon Valley in the 80s through the 00s.