If it didn't matter, why did you bring it up?
As to answer your question - it matters as it generates a false sense of massive public support. Now, I know that there are a lot of people supporting this, but the more inflated numbers are tossed about, the more of a thing it becomes. The moment this half a million, 500k meme is established, then dispelling it by facts is almost impossible. So yeah, not as trivial as you make it to be.
I'm not responsible for what others are posting or what they argue.
I don't think that holding the protest itself should be banned, but I see the date picked and insisted on in a different light than yourself. I also don't see the protests through your, apparently, rose tinted glasses, either.