Fun fact - as I was reading Red October, I got a job as an electronics apprentice/tech at the yard in Portsmouth NH, and the first boat I stepped onto was the Dallas. Was a cool moment.
Like I said, that free visa is for 1 month. You can renew for 1 month if you pay $50 on entry. The free visa you're not allowed to work. So this guy is either there illegally, is doing visa runs to Singapore every month or two, or has some other visa that I'm curious about.
Source: lived there for a while and did a LOT of visa runs
The prerequisite for that, according to [0], is "The Limited Stay Visa, or VITAS1, is a single-entry visa that foreigners may obtain for the purpose of investment, research, work and etc".
Fair enough, so it looks like he's got his KITAS. Bear in mind that's a significant hassle to get and can be quite costly with all the documentation needed. I have a friend who recently got his, as he needed to be the director of a company, and all up I believe it cost around USD$3500.