Encountered the same, a bangla and it was dark at night, luckily managed to brake in time, and the bugger still turned back and gave a typical big bangla smile. He didn't even realise the impact at that speed would have sent him flying.
The indian / bangla / chinese workers not uncommon. In fact, i'd say it's very common. No lights.
I always ride back home (recreational cycling) from MBS/GBTB/MBE area around the time when the chinese workers knock off from the nearby construction around UIC building and collect their bikes at UIC/Shenton house along shenton way. All clad in grey, i rode with them like > 10 times liao.
They do not observe traffic lights one, though luckily they still do check clear quite ok. So the only safety net is their check clear accuracy. Cars / bikes travelling at 60-80kmh would have no chance spotting them until too late. They ride across the road at around 15kmh, no chance.
Some banglas clad in dark blue / black even. Is quite jialat. Just a few days ago i actually cut into the lane of 1 bangla and caused him to e-brake. I could not see him at all till the very last minute.
For foreign workers, the last thing they'd care for is lights and helmets, fully understandable of course, but then the issue and risks are still there.
For reference. Their visilbility is even lower than the grab below