Why Vichy resistance does not excuse the Torch failure

Was it logical for Dönitz to assume Vichy French forces would defend North Africa against Operation Torch?

Perhaps, but that did not explain why his large Atlantic submarine force failed to touch the invasion convoys at sea.

The expected behavior of Vichy French forces was a separate question from the submarines' task at sea. Dönitz had claimed that 100 submarines in the North Atlantic could severely restrict Allied operations. By Torch, he had roughly 196 boats operating across the Atlantic system. The invasion convoys were among the largest formations ever to cross that ocean, yet they passed without the disruption his prewar claim implied. Their survival directly tested his strategic promise and cannot be explained by French resistance on land.