IMO, it's not an "octane" issue. It's just something with that particular race fuel.

It def would have made more with one of the heavily oxygenated race fuels.

I think T&D's mentality on the lube is....... They sort of just assume it's going to be oiled through the pushrods.
In a through shaft oiling scenario, I can see where removing the grease is the better call.
In general, I don't like "grease" type lubes in the rocker gear, because of issues just like what you had. Get the grease out, and do a good system priming right before start up...... That's my preffered method.