> Does this mean that the Go developers managed to work around this problem or that it was just a flimsy post-hoc justification for chronic NIH syndrome?
No, there is almost certainly a bunch of headache having to do system calls through libc for Go. It didn't stop being a problem, there just isn't another option in OpenBSD's case. UNIXs are tricky for anyone who doesn't want to use libc since they typically define that as the official interface to the system. Linux is the outlier here by keeping its syscall ABI very stable.
No, there is almost certainly a bunch of headache having to do system calls through libc for Go. It didn't stop being a problem, there just isn't another option in OpenBSD's case. UNIXs are tricky for anyone who doesn't want to use libc since they typically define that as the official interface to the system. Linux is the outlier here by keeping its syscall ABI very stable.