The Rosenbergs worked for an ally nation. The Soviet Union was our ally in WW II. /end short history lesson
The Rosenbergs may have worked for an “ally” nation during WWII, but continued their espionage activity well into the Cold War period by which time the Soviets had unquestionably become an enemy and threat to the US. And the magnitude of that threat was greatly enhanced by the information passed to the Soviets by the Rosenbergs and others, which facilitated the Soviets’ building of their first atomic bomb.
Maybe the end of a short attention span. The Rosenbergs helped Stalin obtain a nuclear bomb after world war 2 was over and the cold war was on. That was threatening the life of every American. Clearly a totally different case.