"Hey you with the bike. Please move it away from the yellow platform," says the transit security. He was on the other side of the platform. I didn't want anymore attention from anybody. So I folded the bike and put on the quick rain cover. Now it looks like a regular luggage. So by the time the transit security came up to inspect tickets there was no bike nor lecture about safety.
A covered Brompton is easier to lug around inside offices, buildings, airports, cafes, restaurants, and public transport. I don't even bother bringing a lock anymore because it goes with me everywhere. So if you just want to get on with your day without being noticed that you are carrying an extraordinary bike then get the Brompton rain cover.