Wilkie – my best guess, (and that’s all I have is a guess), is that those are artifacts of Peter Cornish’s foundational buffer circuit used in almost all of his designs. I did a bit more poking around in some of Peter’s schematic designs (reverse engineered traces mostly) and that “R38 & R39”, (R29 & R30 – 91 Ω and 51K Ω respectively in Peter’s schematic found here: Cornish Soft Sustain Schematic [SS-3]) seem to be part of his schtick.
Aion, which does a number of traced Cornish-style circuits (for comparative exploration) and also demonstrates the same final resistor elements at the end of their “Cygnus” (a traced P.C. G-2 distortion\sustainer) and “Oceanid” (a traced P.C. OC-1 compressor) builds.
I can only surmise that the final resistor arrangement acts as a sort of ‘bleed’ cushion or path in order to, (at switch time), to minimize any switching noise or popping from either the circuit itself or any potential that may exist in to what it is connected.
So I concur that the impact of the 91 Ω and 50K Ω resistors at the output would & do indeed have minimal impact on the performance and behavior.