Specifying "a people... who give their leadership to a woman" was merely referring to the people of Kisrah, whom (it appears) were unique at the time for having a female leader. Yet it must be understood that the hadith of Abu Bakra is not a blanket statement to be used at preventing women from having *any* positions of authority.
There was another incident wherein this can also be found:
When A'ishah (radhiAllahu 'anha) heard about this, she said, "May Allah forgive Abu Hurairah! He did not hear correctly and thus he is not teaching correctly. The hadith was not said like this. Rather, there was once a man from the hypocrites of Medinah who used to verbally abuse RasulAllah (sallAllahu 'alayhi wa sallam) a great deal. This eventually upset him, and he asked his Companions, 'Who amongst you is willing to protect me from this man?' They told him, 'This man, in addition to his already ugly character, is also a child of zina.' Thereupon RasulAllah commented, 'The child of zina (i.e. this man) is the worst of the three (i.e. even worse than his parents, who committed the sin of zina).'"
And Allah knows best.