Since you mention the SF inspiration behind this, I thought I'd note this question also has relevance to plausibility of the setup of Orson Scott Card's novel "A Planet called Treason" (later rewritten as the updated novel "Treason"), which also centers on an extremely metal-poor planet. (The novel has some SF aspects that may require greater suspension of disbelief, but that's another matter.)

Note: I accepted the other answer which discussed decay further, but this one seemed to provide a suitable answer, too. Unfortunately, I don't have the level of understanding necessary to determine with certainty which answer most deserved the acceptance; I clicked Accept on that one but upvoted both. If it had been possible, I would have split acceptance between the two.

You link to a closed post (that went through numerous revisions before being edited down to a non-question) posted by someone who thinks they have a nearly pure iron meteorite. What is the purpose of the link? Are you asking whether an iron chunk of that mass (a reported 4,902 grams) and that reported purity (99.99%) could be directly ejected by a supernova?

@SteveLinton Yeah, friction/accumulation of low-angular-momentum gas seems like the likeliest explanation. It'd be nice if they explained that clearly.

@uhoh Why would the orbits get closer? Accumulation of low-angular-momentum gas being cast off by the star? Would that really contribute enough material to make up for the fact that, as seen If you do a simulation of a large and small body, and decrease the major body's mass, the orbit of the minor body gets farther, as its momentum caries it along farther without the path being bent as dramatically by gravity. academo.org/demos/orbit-simulator

Like Florin, I wish this answer would expand on this. It doesn't really make sense to discuss "planets being destroyed by tidal forces when their host stars become white dwarfs" without explaining how the new circumstances of the planets (e.g. being drawn into closer orbits) would happen as a result of the transition to white dwarf.

It does affect the addition of leap seconds, according to iers.org/IERS/EN/Science/EarthRotation/EarthRotation.html . Leap seconds have been needed only sparingly, on avarage between one and two a year nature.com/news/2004/041229/full/news041229-6.html (never a subtracted second because the rotation is, overall, slowing down from the 1900 baseline). A given irregularity wouldn't be likely to cause a leap second all on its own -- it'd shift ahead or push back one of the leap seconds that would happen anyway.