Oozie jobs with fork and not using join
From the documentation
The fork and join nodes must be used in pairs. The join node assumes concurrent execution paths are children of the same fork node.'
Also the docs state that,
Oozie performs some validation for forked workflows and doesnt allow the job to run if it violates. However, if you want the behaviour you can disable forkjoin validation so that Oozie will accept the workflow.
For specific workflow, set oozie.wf.validate.ForkJoin to false in the job.properties file.For all workflows, set =oozie.validate.ForkJoin= to false in the oozie-site.xml file
Also, IMPO you can just join and then progress to the end node.