I am not sure if the HSA people has the right to enter without warrant or what but that guy inside his accomodation did the right thing by standing his ground. Fucking throw that piece of paper in their face lah.... anyway from what I see, he did not identify himself as the authorities until much later then the guai lan kia with glasses put on his lanyard to display his identification. So whatever you do to him before that cannot be consider as using criminal force on authorities right?
If can like that anyhow ask people open door claiming to be authorities, isn't that dangerous? Ohh... ever wonder why in Singapore so many kena scams like these.... conditioned from young to fear the authorities is the result. Frankly speaking, the warrant card, lanyard all these can easily be fabricated by anyone with a printer. Who da fuck will ask you to take it out for them for closer inspection of the identification card especially when one has been conditioned to fear the authorities?