How about the narrations coming from Hazrat Ayesha? Some of those narrations are also very alarming. Do you reject those as well?
Also, Abu Huraira (r.a) spent 3 years with the Prophet not 2 and it is a known fact that he basically dedicated those full three years to sticking to the Prophet (PBUH) while the others were busy either attending to their families or businesses. So basically his learning from the Prophet (PBUH) was a full time job for him. Moreover, he outlived the four khulafa' ar-rashidin, and most of his time was spent in teaching the Sunnah and the rulings of the deen, so it is only natural that he should have narrated so many ahadith.
After all, if Abu Hurayrah's Hadith were suspect or worthless, why would so many people be involved in the narration of his Hadiths?
So irrespective of the number of Hadiths a Companion narrates, you could ask the question:
What kept all these Muslims (other Companions; major Tabi'in; the younger Tabi'in; the Imams of the different cities; the Jurists; the Ashab al-Hadith who collected Masanid; the Six Authors, and so forth) look after his Hadith, verify them and use them as authoritative evidences?
Also, he didn't narrate millions of hadith the number is around 5-6 thousand.