Whilst I can't disclose specific details of a private message, I can say that as far as I am aware, Franko's decision to leave is not due to any negative exchange with anybody else here or any ill-feelings about the site. It seems he just wants to return to a quieter life without the web.
Now, it's unfortunate that he's decided to erase his contribution here by editing away his own posts (I did suggest that this was rather futile due to quoting and would leave threads in a mess) but users are allowed to edit their posts and so he's totally within his rights to do so.
Suffice to say it's not site policy to delete user accounts (save the odd purge of long-inactive members), so the door remains open if he has a change of heart.