see https://ugolini.co.th/ugolini/microsoft-says-error-caused-ta... or https://newsasia.co/microsoft-blames-accidental-human-error-...

this code change is in response to the fact that bing was not serving up results of the tank man image on the image's anniversary.

The Tienanmen square protests were protests for freedom, and censoring images does not seem very free.