Denounce also creates liability: you are slandering someone, explicitly harming their reputation and possibly their career.

I'd hesitate to create the denounce function without speaking to an attorney; when someone's reputation and career are torpedoed by the chain reaction you created - with the intent of torpedoing reputations - they may name you in the lawsuit for damages and/or to compel you to undo the 'denounce'.

Not vouching for someone seems safe. No reason to get negative.