The only thing I claim is safe is: 1) its done offline, 2) its done randomly, and 3) no one can know the method of creation. I will stick by that maxim. < this is the essence of the thread
I don't see the need for (3). Indeed, if (3) is at all useful to your security then I'd claim that you're not introducing enough entropy at step (2) and are being forced to rely on the extra entropy of your method being one among many plausible alternatives.
Certainly, 256 coin flips provides sufficient entropy. I believe 128 coin-flips is enough for critical cold storage even with the method known but I'm not a cryptographer.