I worked with the fraud team implementing the security for a real time data ingestion pipeline at a major bank partner. I am a bit more informed on this than the average hn poster :)

It's literally less information versus directly letting them know. One message lets them know you know, and the other doesn't.

> Forcing the fraudster to call if they want more information - excellent.

But there's something else you're not taking into account, which is innocent people who trigger your fraud detection.

>Cussing - doesn’t make a difference either way from an information perspective.

Well it certainly lets the fraudster know you know. A legitimate customer receiving that kind of abuse would be pretty unusual, don't you think?