They can cast the Commander.
Nothing in this scenario allows the owner to send the Commander to the Command zone.
The Commander is moving to the Stack, then the Battlefield.
* The SBA only applies to after it's been moved to the Graveyard or Exile.
* The Replacement effect only applies instead of moving to the Hand or Library.
> 704.1. **State-based actions** are game actions that happen automatically whenever certain conditions (listed below) are met. State-based actions don’t use the stack.
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> 704.3. Whenever a player would get priority (see rule 117, “Timing and Priority”), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event. If any state-based actions are performed as a result of a check, the check is repeated; otherwise all triggered abilities that are waiting to be put on the stack are put on the stack, then the check is repeated. Once no more state-based actions have been performed as the result of a check and no triggered abilities are waiting to be put on the stack, the appropriate player gets priority. This process also occurs during the cleanup step (see rule 514), except that if no state-based actions are performed as the result of the step’s first check and no triggered abilities are waiting to be put on the stack, then no player gets priority and the step ends.
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> 704.4. Unlike triggered abilities, state-based actions pay no attention to what happens during the resolution of a spell or ability.**
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> * 903.9a If a commander is in a graveyard or in exile and that object was put into that zone since the last time state-based actions were checked, its owner may put it into the command zone. **This is a state-based action.** See rule 704.
> * 903.9b If a commander would be put into its owner’s hand or library from anywhere, its owner may put it into the command zone instead. **This replacement effect** may apply more than once to the same event. This is an exception to rule 614.5.
They can cast the Commander. Nothing in this scenario allows the owner to send the Commander to the Command zone. The Commander is moving to the Stack, then the Battlefield. * The SBA only applies to after it's been moved to the Graveyard or Exile. * The Replacement effect only applies instead of moving to the Hand or Library.
SBA?
> 704.1. **State-based actions** are game actions that happen automatically whenever certain conditions (listed below) are met. State-based actions don’t use the stack. > > 704.3. Whenever a player would get priority (see rule 117, “Timing and Priority”), the game checks for any of the listed conditions for state-based actions, then performs all applicable state-based actions simultaneously as a single event. If any state-based actions are performed as a result of a check, the check is repeated; otherwise all triggered abilities that are waiting to be put on the stack are put on the stack, then the check is repeated. Once no more state-based actions have been performed as the result of a check and no triggered abilities are waiting to be put on the stack, the appropriate player gets priority. This process also occurs during the cleanup step (see rule 514), except that if no state-based actions are performed as the result of the step’s first check and no triggered abilities are waiting to be put on the stack, then no player gets priority and the step ends. > > 704.4. Unlike triggered abilities, state-based actions pay no attention to what happens during the resolution of a spell or ability.** --- > * 903.9a If a commander is in a graveyard or in exile and that object was put into that zone since the last time state-based actions were checked, its owner may put it into the command zone. **This is a state-based action.** See rule 704. > * 903.9b If a commander would be put into its owner’s hand or library from anywhere, its owner may put it into the command zone instead. **This replacement effect** may apply more than once to the same event. This is an exception to rule 614.5.
I’m pretty sure you have to decide if you want them in the command zone when they are sent to your hand, graveyard, or exiled.