The specified alignment makes the United States the only workable destabilizing power. A reckless British policy could fracture German or Italian support, expose Canada and the wider empire, and offer London no useful strategic gain. Producing that policy would require factions far from power to abandon basic imperial risk calculations. Earlier operations alongside Germany had failed to redirect German policy, so another shared war offered Britain little reason to force a new partnership.
Notable Point · 30:58-40:15
Why Britain does not work as the counterfactual aggressor
The specified alignment only works if the United States becomes the destabilizing power, since an aggressive Britain would risk its empire and might lose German or Italian support.