He said greater than 10,000 years, but not a specific number. You have to understand that there are always limiting factors in nature as to how quickly populations can grow and die. 1.6x normal growth rates on average can be disastrous, even if the organisms are capable of it. Consider algal blooms, for example, and how the have this tendency to poison the marine life around them.
Furthermore, when such growth happens, the organisms involved die off very fast thanks to overcrowding, reducing how much they would grow in population by a significant extent for the next few years.
Also, consider the fact that the flood would have wreaked marine life for centuries. That's right, centuries, and I am being generous with that. There should be a huge gap in those chalk deposits that have different sediments if the flood occurred, because nearly the whole population of all marine life would have died.