Rabbi Greenspan, Joseph explicitly made that claim. That’s why I challenged it. He was NOT referring to Yom Hashoah. He never even mentioned it — I did, as an example of a date which the Rabbonim did object to, as opposed to Yom Hazikaron, which they did not.
And it simply doesn’t matter who chose the day or why. The fact is that this is when these kedoshim are memorialized, and we should not be poresh min hatzibur.