Or he's now on medication for trying to surface grind a No 6 plane with half a gravestone and a broken shop window to engineering tolerances that even NASA finds redundant?
I have to question the rationale of having to have permanent access to surface plates for a small finite set of hand planes. I get it if that's something you do to each new plane you come across and you come across loads but to just finish your own hand tools is a tad OCD. Do it once on a piece of sufficiently thick float glass and Robert is very much your fathers' brother. If you really crave the tolerance get the local machine shop to surface grind it for a box of beer or bragging rights on Instagram.
The thing is if you took two planes, one surface ground on an AA graded plate and the other lapped on a piece of float glass from the local glazier, you won't be able to measure the difference of the two on the actual material being worked, i.e. wood.