Promised Messiah(as) always said good things about Abu Hurairah(ra) . He said he had a weakness not that he was stupid God forbid. In the messiah(as)’s books he continuously says good things about him and all of the sahaba. The book where Mirza Ghulam Ahmad(as) has used the word ghabi is not in Arabic. There is a difference between the language Arabic and Urdu and all sincere readers would know this. In Urdu, this meaning can mean not the best in dirayat or interpretation.
In the non Ahmadi Book in regards to the principles of Ahadith, Usulush Shashi, it is stated:
The second category which exists among the narrators of Hadith is of those who are renowned for their remarkable memory and honesty, but cannot be relied upon for their Ijtihad or religious verdicts, such as, Abu Hurairah (ra) and Anas bin Malik (ra).”
Ibn Hazm and many other great scholars have also mentioned this.
The Promised Messiah(as) also said this and it’s the same reason for why Hazrat Ayesha(ra) and others used to explain many things to Abu Hurairah(ra) when he would make mistakes in interpretations. Ghabi does not mean stupid here and once again this is written in Urdu. It means not understanding or being able to explain certain points. It has many meanings and he explained what he meant throughout the page. There are many more non Ahmadi scholars who have said along the lines as the non Ahmadi book quoted above and most knowledgeable non Ahmadis are of this as well.