Is a defamatory brick lashon hara?

In this Curb Your Enthusiasm clip, the rabbi says that there's nothing in the Torah about defamatory bricks, but I think it's clearly an example of lashon hara.

But then one might argue that it's not lashon hara because it's a sort of warning?

What do you think?

https://www.youtube.com/watch?v=9i0V985lpnc

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serge β€’