Portableapps dot com has been going since 2004 and is a legitimate company, they DO NOT "knockoff" software and have been recommended by CNET, PC World, Wired, Lifehacker and more. They are fully transparent about what their company does and licensing.
To quote them, the download they provide "assists with running CCleaner® portably" and:
Online Installer: The ccPortable installer will download the base app from the publisher's server during installation. CCleaner® is a registered trademark of Piriform Ltd. PortableApps.com is not affiliated, sponsored, authorized or otherwise associated by/with Piriform Ltd or its associated companies.
Given the base app is pulled from the Piriform site I consider it safe. I do not promote the use of dodgy unlicensed software...just saying
Also, @hazelnut it might be worth reaching out to them, I am sure they want to be compliant with your copyright/trademarks/IP/...