You can light TNT in spawn protection, through the use of a flame bow

• Start a server and join it
• Give yourself operator permissions
• Set the world spawn to your current location
• Place a block of TNT or TNT minecart within spawn protection
• Obtain a bow enchanted with flame
• Give operator permissions to a different player
• Remove your operator permissions
• Shoot the bow at either TNT or a TNT minecart within spawn protection
  -Notice how they are lighted and destroy blocks within spawn protection