That's a valid point.
Unfortunately, the JiraTestResultReporter plugin does not have features to dynamically assign owners. Additionally, I don't think it is always easy to find proper owner for post-commit tests at first glance, since they usually cover broad specter of issues.
My assumption is that we need someone to triage new issues.
Ideally, any contributor, who sees failing test, should check unassigned tickets and either do triage, or assign them to someone who can. I strongly encourage this approach.
We have couple other ready-made options to consider:
1. We can configure JIRA component owner who would be assigned to created tickets.
2. JiraTestReporterPlugin can assign tickets to specific user. This is configured per Jenkins job. We can utilize this if someone volunteers.
3. Dynamic assignment will most likely require custom solution.