Even if that analysis were accurate, that isn't mining "in private" before "publicly launching" as you claimed.

That's fair, my memory was incorrect. However, I don't think that makes a difference w.r.t. calling the coin premined.

I do not think the term should be used in this case because anyone could've mined at that point; others that actually did pre mine did so when only a few insiders could as well, like a pre IPO.