Late to the party here, but yeah that was my take as well. As the inner simulation was about to burn planet express down, the professor made a comment about how catastrophic it would be given all the "doomsday" devices he has. I inferred that to mean that if all those doomsday devices went off, the outer simulation would be unable to simulate it, revealing that the "main" simulation was a simulation in itself; so outer bender came to the "main" simulation with the intention of stopping that from happening.
Late to the party here, but yeah that was my take as well. As the inner simulation was about to burn planet express down, the professor made a comment about how catastrophic it would be given all the "doomsday" devices he has. I inferred that to mean that if all those doomsday devices went off, the outer simulation would be unable to simulate it, revealing that the "main" simulation was a simulation in itself; so outer bender came to the "main" simulation with the intention of stopping that from happening.