Is this a real question? Instead of justifying the choice to use something good without taking the bad bits too, let me pretend you asked “what are the advantages of using the BSD userland”.

I am not a Chimera dev and they have answered this but here is what I understand….

You could argue that the GNU utils are bloated and over engineered. But that is just an opinion. As the Chimera devs point out, there is a “chicken and egg” dependency problem with the GNU utils when trying to build from source and / or in a container. The BSD utils solve this problem.

At the same time, the BSD utils are more complete and powerful than, for example, Busybox or other alternatives to the problem above.

The BSD userland solves one of the problems that Chimera Linux is trying to solve. The BSDs do not solve many of the other problems and so using everything from BSD is not an option.

I will point out that Chimera Linux and FreeBSD both use Clang/LLVM as the system compiler. Chimera uses it for LTO and certain security features.