Veg oil seems like a bad call for shelf-stability. Sure you can boil off any dissolved O2 and N2 sparge the bottle before sealing it, but that only helps you until you open the bottle.
Veggie oil will go rancid without any help from bacteria.
That being said, Bailey’s isn’t that shelf stable and will likely turn into undrinkable too faster than the average veggie oil will go rancid. And veggie oil can be stabilized to some extent by adding vitamin E.
