I would point out you likely would not be sued for defamation.  At least not in the US.  Most people don't realize how (almost impossibly) difficult it is to win a defamation/slander suit in the SU.

The first amendment has (somehow despite the slow erosion of liberties) managed to keep the burden of proof very high.

Generally speaking (although statutes vary by state):

• The statement must be false.
• The defendant must know the statement is false or a reasonable person would determine the defendant should have known the statement is false.
• The plantiff must suffer a loss (one recognized by the court as compensatable damages) as a result of the statement.
• The plantiff must be able to quantify and prove the loss.

The burden is very high.  Plenty of people accuse other people of running Ponzi and don't get sued.   Hell some investment brokers accused Madoff of running a ponzi for YEARS before the ponzi broke.  Proving all four elements is extremely difficult even in the best circumstances.  It is possible that defamation actually occurred and yet it simply can't be proven.  I am not saying the plantiff's lawyer did a bad job, I am saing it simply not possible to prove defamation in all cases.  The Supreme Court ruled that while the high burden will allow unanswerable accusations to do otherwise would have a "chilling effect" on free speech.

Even then there are interesting carve outs like the Small Penis Rule.