Yes, I've read those. And it does not specifically state that you must upgrade first and only, then do a clean install.
It speaks to having to do a subsequent clean install later, if desired. For that, the answer is yes.
The question of "Can I do a clean install first" has not been fully answered.
However...this PowerPoint slide from January seems to suggest yes, you can do a clean install via an ISO file:
If not for a clean install from the beginning, of what use is obtaining the ISO file upfront?
As always:
"However, the official response from a Microsoft spokesperson when it comes to Windows 10 is “We look forward to sharing more details about how the upgrade will be offered at a later date.” "