Not only is the damage contained, but it is also much easier to protect an isolated NFS server.

For instance, instead of being able to read/write/jump literally anywhere in memory, it would only have capabilities to the resources it needs.

And these capabilities would be enforced strictly, by the bug-free microkernel. The likes of seL4 even have formal proof of correctness.

And you are still making these arguments on the discussion of a bug that they have absolutely no bearing on. If Linux were written with the same exact development history, but as a microkernel, the exact same bug could (and likely would) exist in the NFS client component. The impact is spurious unavailability of service, and would be the same on a microkernel; it is not exploitable for memory corruption. And any file system service, by its function, will be in a position of relative privilege, even if less so on a microkernel.

Your arguments are likely valid, with other bugs. Please take them there. Wedging this discussion in here just makes you look like a proselytizing zealot.