Originally posted by Darth Jello
according to George Lucas' hint, any jedi that was shown on screen in episode II could have erased the files.
Deflok, why would Mace and Yoda want to kill a fellow jedi??
But what Sifo was doing incredibly evil things and confronted Mace or Yoda in a lightsaber battle, they could've 'killed' him by accident.
Even if they did go back to find the remains, it's entirely possible that the means of Sifo's demise could have destroyed every particle of his body. Or he could've been left somewhere that would be impossible to return to, like a planet on the brink of volcanic destruction, by the time they go back the place could be a molten mess.
a Jedi can per definition not do anything evil
a Jedi stands for good and pure, he can't go bad in one day, just for the joy of it.
Dooku left the order and LATER got corrupted, and anakin...well, he's the chosen one 😉
still, no matter the conditions, a jedi would still go back to the body, no matter in much danger they are