Offering API-compatible tools is very deeply ingrained in the UNIX philosophy; just think of the different implementations of "ls", or the C functions mandated

Offering API-compatible tools is very deeply ingrained in the UNIX philosophy; just think of the different implementations of "ls", or the C functions mandated by POSIX, or the way that clang (the compiler targeting LLVM) has the same flag names as GCC, which probably copied them from somewhere else in the first place... Generally, if you publish an Open Source project, you cannot complain if people copy parts of it, even it's the command line arguments / API / whatever.