I'd say slim to none.
They haven't previously been charged with a RICO predicate offense, but RICO doesn't require you to be separately charged with a predicate offense (either before or concurrently with RICO charges), only that the required relation to a predicate offense be in the allegation supporting the RICO charge. In fact, the central point in RICO is to allow charging people/orgs involved in schemes to promote predicate offenses for commercial benefit who might not otherwise be able to be charged as principals of those offenses.
It's not like Amazon does this without any costs on their ends.
If they complain about the ethics of industry are low now wait until they cause "Johnny Tightlips" to become the safe legal standard.
https://www.popehat.com/2016/06/14/lawsplainer-its-not-rico-...
Even secondary sellers of counterfeit goods? Of course they are.