Sounds like deflection of their own inability
As a product owner, their core function is to know what is most import based on the stakeholders input for teams to work on. If they cannot prioritize the product(s), and their respective defects, that they are responsible for, then I wonder what they are doing with their time.
If they need more time to do their job, then they need to schedule time for themselves. I do the same thing by making a meeting to block off time.
By making a story, it now becomes the scrum team's responsibility.
Now, everyone does scrum/agile differently, but here are a few things to consider that may or may not apply to how your company works:
If it's a story, that is something that cuts into the team's velocity. Even if it's assigned to the PO, the theory of agile is that anyone in each scrum team can take it. So they are wedging in this "story" with a time box that they personally will not be able to resolve in that time (otherwise it would have already been done). So someone else will need to step up and do the work. If it gets done, the PO is the hero for getting the defect prioritized. If it doesn't, the team fails because there are incomplete stories at the end of the sprint.
Also, depending on how your teams work, defect work is not pointed; it's tech debt. So they are adding more debt to the team to figure out what debt should be paid off first.