Unlike a wartime situation, where the senior ranking member takes command of all prisoners, in a hostage situation, the most capable member must take command to ensure survivability.

That statement is false.

Even in hostage situation, the chain of command is still exist and must be followed by all members of the army.

As hard as it is to say, the military need to consider the amount of expense and damage that might happen because of the hostage situation. Sometimes they may choose to leave the hostage to ensure the survivability of others