What would that change, effectively, other than have Apple lose money?

The UK would still lose ADP (and then also just Apple products in general). A precedent would still be set.

Your posing a strictly worse third option. Sure, it's an option, I guess. Apple could also just close down globally, as a fourth option. Or sell off to Google as a fifth. But I was trying to present the least-bad option (turn off ADP), rather than an exhaustive list.