By 1944, this wasn't much of a risk. Even if you assume it was, it would be a violation of the Quebec Agreement that was signed in 1943. Violating that part of the agreement casts doubt over which other parts of the agreement that they would violate. The US post war strategy was always a concern, more so during what was an election year.

Great Britain's outrage is understandable.

I'd argue that agreements mean much less when genocidal dictators can obtain nuclear weapons.

Also, even if a situation ends, we'll always feel that it's decently probable it can happen again throughout our lifetimes. Ex: Anyone who lived through WWII is much more concerned (and rightfully so) that it could happen again.

The fact that Britain was nearly conquered in 1941 would be enough, with that bias considered.

The deal was signed knowing there was a possibility of the Germans intercepting the bomb. That risk was known, it does not justify reversing the decision.

>Also, even if a situation ends, we'll always feel that it's decently probable it can happen again throughout our lifetimes

Yes, and imagine how terrifying that scenario becomes if the enemy has nuclear weapons and you don't.

>The fact that Britain was nearly conquered in 1941 would be enough, with that bias considered.

Nearly conquered is a massive overstatement for a start. If you consider that too much of a risk to allow Britain to have nukes, the Business Plot was enough to forbid the US from having nukes.