Maybe it's true. It happened to me when I was about to leave for Singapore as a tourist but I was having my OFW passport and I was refused at the immigration. He said I need to have a tourist passport. So I got delayed and have to get a tourist passport. In your case maybe he was having a tourist passport then immigration has a reason to stamp his passport not allowed to work since he is a tourist and going to a country that is hiring Filipinos OFW'S. This is to prevent undocumented OFW or smuggled Filipinos disguised as tourist but will be looking for jobs once they reach their final destination. This modus operandi is not new with some crooked immigration officers in cahoots with the smugglers. Maybe it is the policy of PNOY administration to be vigilant about this human smuggling. You can ask the Philippine Embassy for proper guidance and information.