John, I don't understand.
If neither end is shim6-capable, it is resoundingly out of scope.
If only one end is shim6-capable, we can't run shim6, so we have to revert to mono-homing.
I guess Marcelo's point is that there a number of different "modules" that we need for the SHIM6 to work. One of those modules is relatively simple, and deploying just it without anything else would also bring benefits.
--Jari