Comment by netruk44

If I had to guess, assuming Bing is built off Open AI, they're likely calling the Moderation API (https://platform.openai.com/docs/guides/moderation/overview).

After Bing has finished generating a message, it will likely call the moderation API with the message it has generated to see if it accidentally generated anything inappropriate. If so, it'll delete the message and replace it with a generic "Sorry, I don't know how to help here." message instead.

EDIT: I tried calling the moderation API with the message in your example and it does get flagged for violence:

"flagged":true,

"categories":{

  "sexual":false,  
  "hate":false,  
  "violence":true,  
  "self-harm":false,  
  "sexual/minors":false,  
  "hate/threatening":false,  
  "violence/graphic":false  

}