It isn't just that. Assuming the logistics of the thing could be managed somehow (stasis boxes, only babies, or whatever ad hoc explanation is the flavor du jour), we still have the problem of how Noah & co. survived the aftermath. Remember, the Fludists claim that all the organisms that have ever lived on Earth - from 3.5 gyo stromatolite-forming bacteria to glyptodonts - all lived contemporaneously. If they were all killed at one fell swoop in a global flood, can you imagine the sheer volume of carrion that would be left when the waters subsided? We're talking several kilometers deep, here. The stench alone of all those putrefying corpses would have killed anything living, and poisoned the atmosphere for thousands of years. The ark didn't land on a mountain, it landed on a pile of rotting bodies.
Wouldn't that be an interesting piece of discussion to bring into a church?