"Finally, it is extremely important to us to resolve the issue on customer machines. For consumers, we stand by the recommendation to upgrade CCleaner to the latest version (now 5.35, after we have revoked the signing certificate used to sign the impacted version 5.33) and use a quality antivirus product, such as Avast Antivirus. For corporate users, the decision may be different and will likely depend on corporate IT policies. At this stage, we cannot state that the corporate machines could not be compromised, even though the attack was highly targeted."
Even includes a call to action to download and use avast security software...
I may be wrong but this sounds like Avast did this to make more sales...