If a player casts an instant or sorcery spell, Hive Mind’s ability triggers and is put on the stack on top of that spell. Hive Mind’s ability will resolve first. When it does, it creates a number of copies of that spell equal to the number of players in the game minus one. First the player whose turn it is (or, if that’s the player who cast the original spell, the player to that player’s left) puts their copy on the stack, choosing new targets for it if they like. Then each other player in turn order does the same. The last copy put on the stack will be the first one that resolves. (Note that the very last thing to happen is that the original spell resolves.)
Rule 706.10c. Some effects copy a spell or ability and state that its controller may choose new targets for the copy. The player may leave any number of the targets unchanged, even if those targets would be illegal. If the player chooses to change some or all of the targets, the new targets must be legal. Once the player has decided what the copy's targets will be, the copy is put onto the stack with those targets.
Rule 101.4. If multiple players would make choices and/or take actions at the same time, the active player (the player whose turn it is) makes any choices required, then the next player in turn order (usually the player seated to the active player's left) makes any choices required, followed by the remaining nonactive players in turn order. Then the actions happen simultaneously. This rule is often referred to as the “Active Player, Nonactive Player (APNAP) order” rule.
Rule 405.3. If an effect puts two or more objects on the stack at the same time, those controlled by the active player are put on lowest, followed by each other player's objects in APNAP order (see rule 101.4). If a player controls more than one of these objects, that player chooses their relative order on the stack.
Hive Mind's ruling is focusing more on the order they end up on the stack, not whether the spells can target each other. It could certainly be worded better to be more generic and accurate for more use cases, but it's not really wrong.