One of Mozilla's central data protection principles is No Surprises.
I damn well hope that the download link will be clearly marked as an altered version of Firefox, explain that the complete browsing history will be collected and analyzed, and will preclude absolutely any way to accidentally download it without understanding the risk.
Did you mean to say “all links visited in the Cliqz-enabled browser”, or otherwise does the post somewhere express any intention to collect visit data from prior to Cliqz?
"This version of Firefox will send your browsing history to a third party, Cliqz, for analysis and suggestions".
When i download Chrome, i know where my history goes - to Google. I also know where it doesn't go - somewhere else.
And secondly, Google can do a lot more with your data than Mozilla and that third party combined could ever do, both from a technical viewpoint in terms of evaluation, linking to other data, distribution, and especially so from a legal viewpoint.
Providing this information as you put it would be entirely misleading, even if it is factually accurate in isolation.
The article doesn't say prior history won't be collected, and the grandparent didn't say it will be. If you want to be pedantic, someone installing Firefox from the main download page probably won't have any prior history.