He killed only Hindu prisoners before coming to Delhi and while plundering Delhi, he said "sayyids (or lineal descendants of the Prophet), shaikhs, and learned Mussulmans should be preserved", so there was an overall bias.
Refer to my earlier comment on judging medieval rulers through the lens of temporal relativism. He opposed anyone who stood in his way to power and immortality, Muslim or otherwise. Many Muslims he regarded as unworthy or undeserving of stewardship over their empires. Many Muslims he had personal beefs with or felt insulted by some troll exchange about females (this is at least part of the story with Bayezid). The guy was a reasonably straightforward warlord, who produced very impressive results and didn't do anything "immoral" that contemporaries in Europe and elsewhere didn't do.
The inferiority complex is quietly seeping into this thread, which is a shame, since it's a great historical discussion. What's next? Shall we dredge up Saif Ali Khan and his kid? Some of the vitriol directed at his baby on Twitter was downright terrifying and is rooted in the same inferiority complex about medieval history that I refer to. It's the 21st century and folks wished death and zika virus upon a baby because his name was Timur.
The fact is, Timur was the precursor and direct ancestor of the Mughals. He gave rise to one of the greatest and most artistically influential empires Asia ever did see. Timur himself was somewhat one dimensional but he spawned the builders of a unified, independent and strong Hindustani nation.
I think Timur should be REVERED in India and not villified, the same way as emotionally stable populations in Europe revere and respect their equally brutal precursors and forefathers (Romans, Greeks, Saxons, Celts, Vikings etc). Take England for example. Celts, Romans and Vikings literally butchered entire cities including children and females without any problem whatsoever. Yet I can guarantee you, no modern Brit will curse a baby named after Harald Hadrada or Claudius of Rome.