Just curious.
At which point do you disagree.
This is the part I disagree with:
Nobody can put any licence on public domain.
(edit) and also/especially:
Licencing the whole thing under the MPL was illegal.
If something is PD it has no license or restrictions at all attached to it. Therefore, anybody can copy, license etc as they see fit. Therefore I don't see how it can be illegal to relicense.
However, once something is PD, it remains so, so if anybody else wants to copy the exact same thing, no problem. As long as he/she only takes the PD parts.
Perhaps in practice/in the end we more or less agree

@Marco: common law systems indeed differ wrt copyright etc. AFAIU you can relinquish all copyright by placing things into PD.
IIUC, even under civil law systems, you can relinquish a lot of your rights, including rights to reproduce, but you cannot relinquish certain moral rights (once again, IIRC) e.g. the right to be called the author.
I presume
www.iusmentis.com has some articles on this... yep, see e.g.
http://www.iusmentis.com/computerprograms/licenses/choosing/