This is what I meant. Both cases are ambiguous; you're arguing in favour of re-ordering the list, not against the Oxford comma. And since the Oxford comma resolves ambiguity in many other cases, I don't see why you would argue against it.
Because any case where the Oxford comma could resolve ambiguity could have the ambiguity resolved in another way. I view it as an intrusive and unnecessary punctuation point. Using the Oxford comma to maintain a list's order for stylistic reasons is essentially using poetic license on punctuation, which is something I don't hold with.
Some examples from the wiki page;
They went to Oregon with Betty, who was a maid and a cook.
They went to Oregon with Betty, both a maid and a cook.
They went to Oregon with Betty (a maid) and a cook.
They went to Oregon with Betty – a maid – and a cook.
They went to Oregon with the maid Betty and a cook.
They went to Oregon with Betty and a maid and a cook.
They went to Oregon with Betty, one maid and a cook.
See, maybe we just speak the language differently, but I couldn't disagree more. I would always pronounce the pause before the "and". Pronouncing it otherwise makes it sound like "Spain and France" belong together. Think of the length of the pause between "Portugal" and "Spain" when you say that; is the pause between "Spain" and "and" really shorter? Because if it isn't, there needs to be a comma.
When I speak, the pauses are always identical;
Por-tu-gal,-Spain-and-France
1-and-ah-2-and-3
If I want to introduce a longer pause for emphasis, I add them consistently;
Por-tu-gal,-pause-Spain-pause-and-France-pause
1-and-ah-beat-2-beat-and-3-beat
But when I read the list with an Oxford comma, this is what I get;
Por-tu-gal,-Spain,-and-France
1-and-ah-2-beat-and-3
The Oxford comma is like an unnecessary and annoying speed bump that serve no other purpose than to break my rhythm and make me hit my head off the ceiling.