Like any good speed-run getting the quickest time usually involves pushing the limits of the game’s ruleset and gameplay mechanics. Sometimes that involves what feels like a clear exploit or glitch and other times it is just using the rules and mechanics of the game to their extreme fullest, resulting in events that would seem unintended to many players.
For example, IO don’t forbid you from taking the virus out at range in the cave lab in Sapienza with a well placed shot but it would probably come across as an unintentional elimination method to a lot of people upon discovering it.