Crikey was it something I said? I've been trying hard to understand your trails of thought but I must confess I got lost at about the Darwinism comment...
Good find about the Ireland document by the way.
Anyhow, had enough to drink now, so up in the loft I've been, complete with vials of meths, white spirit, petrol and acetone. And camera.
Some of my lighting cables have been sunk in polystyrene for somewhere between 5 yrs (when we moved here) and 15 yrs (last "proper" electrical work/check)
Meths and white spirit don't touch the stickiness. Acetone cleans off the polystyrene sticky but makes the pvc a bit sticky too. Petrol works a treat, and doesn't appear to affect the pvc at all.
Now i'm no chemical expert, and I will eat my hat if the cables degrade tonight amid the remaining fumes and we evacuate a burning edifice, but I dont think so.
Interestingly (even more so) the second cable I looked at had dissolved the polystyrene into a film on the cable which I could peel off like a strip of dried PVA glue, without appearing to have affected the PVC at all.
And as far brittle? Feels and looks and flexes as if completely unaffected.
So there, science practical lesson over and all flammable solvents safely stored away (glug).
But to get back to the OP, I can't believe that a years worth of a few polystyrene beads is enough to warrant the cable unfit for purpose or a danger. Especially if you expect the electrician to replace the first leg of every circuit and more.