Well, the file was found on his laptop and laptops are pretty much exclusively using SSDs. On SSDs a simple `rm` is enough. On an SSD:

    1. You run rm
    2. Your filesystem uses trim to mark the pages as invalid
    3. The drive's garbage collector finds blocks containing invalid pages and consolidates valid pages into new blocks and marks the old blocks as invalid.
    4. Then the drive resets the block to empty and marks it as available.

This improves write performance because SSDs can only write to empty pages (they cannot overwrite pages that have already been written, instead they'd have to first reset the page and then write a new page) so by proactively resetting pages, they have pages ready to be immediately written.

But this also means that the blocks containing your deleted file will be proactively reset/emptied which means it will uncharge the cells which is equivalent to all the bits being `1`, thereby destroying the file.

Source: https://kcall.co.uk/ssd/index.html