What does it mean that there wasn't preponderance of evidence to support an allegation
There wasn't enough evidence to support someone's claims in a civil suit to receive a judgment.
The evidence to tip the scale in his favor was not there. There was "reasonable doubt" created to not support/ believe the allegation.
The plaintiff is responsible for providing evidence to prove his/her allegation. If they are unable to provide enough evidence, then the claim is dismissed. That's how our justice system works.
Preponderance means more likely then not.