Your original argument was that C++ and Swift fit the bill as well. Now, as far as I can tell, you seem to be saying that C++ and Swift are better choices because Apple owns compilers for them. That is a different argument, which is in direct conflict with the one I originally responded to. My response was based on the assumption that you meant what you wrote.

Anyway, onto your current stance. That Apple don't use Swift or C++ for their spider seems to indicate that the benefit of using Go outweighs the benefit of using a language they own the compiler for. Go has a BSD-style license, so as far as Apple implementing their own changes and doing whatever they want with the source code and their own binaries at will goes, they might as well have owned it. Go is also seems like a no-brainer choice for a web spider since it has concurrency modeled in such a straight forward and cruft free way.