As Embury says, there's some sense in using a Scotch-based liqueur, and although this version of the Bobby Burns is rarely seen, it's worthy of a trial
There's a minor typo in the "History" section, "Rob Rob" for "Rob Roy." But the drink itself is lovely--this spec, as given or lightly modified, allows the spirit to shine more clearly than many Bobby Burns builds. This might become my go-to for this cocktail when using single malts in general, but especially for subtle or delicate expressions.