Very odd to hear that from Golang co-creator. I don't really see how Go actually could compete with C++. Maybe in few cases, when people have accidentally chosen C++ incorrectly for their projects.
Rob probably assumed Go could displace this. And it's not unreasonable to assume so, although it's closer to a better Java, than a better C++ for this.
Instead it displaced Python for this (not for research/NumPy/Colab stuff), maybe some Java (where it's easier to containerize).
And if it did displace C++, it was in greenfield projects, with non-C++ developers. So it didn't necessarily convert any C++ developers at all.
I could easily imagine him thinking Go could make inroads there. But then it took a very long time to get a flume port, and even then it didn't have half of the nice affordances that the C++ version did.
People say they need the efficiencies of C++, but IMHO they really don't when so much of the actual code time is spent slurping data from one sstable and writing it to the next sstable.