They dont know who Timur was???
Hehe yeah, just being pedantic, but also I thought you genuinly thought Timur is a traditional Mongol (and not just laying it down for these laymen, hehe), when he is more of ze distant relatives kinda Mongol after their expansions century ago.
Btw, dont know who this Sultan was, but even if funny, I doubt the validity of that account of how he was treated. Timur was usually quite gentmanly and treated his prisoners well, perhaps some truth to it, but doubt it was that clear cut.
Those turkic mongol tribes could be rather savage (this dude ruled briefly, but massacared insane amount of people), but when they have a esteemed "guest", their decorum says they oughta treat him well. Not that was the case all the time, and also it wouldnt the first time unreliable accounts paints history to how the world sees it.