It seems that our cynicism about the "free" status of software and services is ultimately overridden by the fact that we'd rather do anything than cough up money to use them.
I have been using it and Malwarebytes for years and have had no issues.
Recently a message appeared, asking me to click to update to the latest version.
This turned out to be a 30-day trial for their subscription service costing £60 per year. Obviously AVG would like you to subscribe to its paid-for products, but a lot of users have been caught out by this heavy-handed tactic, and it is not making many friends by complicating the exit from the 30-day trial.
In cases where actual malware is found, the packages are subject to removal. Moderators do not necessarily validate the safety of the underlying software, only that a package retrieves software from the official distribution point and/or validate embedded software against official distribution point (where distribution rights allow redistribution).
Chocolatey Pro provides runtime protection from possible malware.