From A complete guide to Super Metroid speedrunning
WORLD RECORD RECORDING
This category uses the route set by Nintendo Power in the Player's Guide; the order of items and bosses stated by Nintendo Power must be followed exactly.
From Ponk, given on Discord:
There has been a discussion about the rules and order in which to finish certain objectives. Basically the point of the discussion was that the rules enforce finishing objectives in the order given by the nintendo power guide. However this left an uncertainty about when the "Defeat X" goal is actually achieved and if its possible to finish the next objective (i.e. picking up an item) before the actual death flag of a boss is set but after dealing the "death blow" to said boss. After debating the intentions behind the run and the exact wording, the official decision on this issue is now that a boss being defeated is NOT the same as a boss being dead. For this matter it is explicitly allowed to pick up the Croc E-Tank before Crocs drops spawn (but after pushing him into the acid) and to pick up the GT-Supers before GTs drops spawn (but after he starts exploding).