I think the discussion was started about Ahmad not `Abdallah.

Enough is the former's declaring `Ikrama the mawla of Ibn `Abbas a liar [even though Hafiz said he is thiqa thabt in Taqrib and refuted all the accusations against him in Hadi al-Sari] in his Fath al-Malik al-`Ali and the latter's praiseful reference to this book in his notes on Maqasid of al-Sakhawi to show how good they were with Hadith.

Ahmad, particularly, is known even today for weakening estabilished narrations and estabilishing forged narrations for whatever purpose he needed to forward.