What this feature aims to solve:
Regarding security issues, I do not think this feature will be effective. There are bots which make use of Github API to look for credentials of AWS/Azure/Google Cloud, etc. People will simply create bots for scraping issues and saving them to archive.is or similar sites. Since the issue deletion involves manual intervention, the delete action will merely remove it from the project page and not necessarily from public record.
Spam and duplicate issues can already be closed. I am not sure if deleting them solves any problems.
It can be useful for the last category of issues but there is already an option for locking issues and moderating abusive comments.
And like any tool, there is always potential for misuse e.g delete genuine bugs without justification.
We will have to wait and watch how the community uses this feature.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.