What I mean is: There will be bugs* in that pure Go implementation, and static linking means you're baking them in forever. Why is this preferable to dynamic linking?
* It's likely that C implementations will have bugs related to dynamic memory allocation that are absent from the Go implementation, because Go is GCed while C is not. But it would be very surprising if there were no bugs at all in the Go implementation.
They're prioritizing memory corruption vulnerabilities, is the point of going to extremes to ensure there's no compiled C in their binaries.