Like I have written before, MGA and his team copied from Sir Syed on almost every single topic, except Jesus in India, that was tooo ridiculous for any human to conjure up.  In this specific case, I have a scan from the writings of Sir Syed, pre–1891, wherein he says that all hadith on the Mahdi are weak and unreliable.

The scan from tahdheeb al ikhlaaq, vol -7, August 1877