This is alarming but I'm not sure the study actually finds that "Wikipedia influences judicial behavior" in the way most readers would understand that term - influencing decisions and sentence.
It finds that "Getting a public Wikipedia article increased a case’s citations by more than 20 percent." That could mean judges are citing cases with wikipedia entries rather than similar cases without and their judicial behaviour remains the same.
It finds that "Getting a public Wikipedia article increased a case’s citations by more than 20 percent." That could mean judges are citing cases with wikipedia entries rather than similar cases without and their judicial behaviour remains the same.