The slots were originally made available as competition remedies and Flybe (V1) was deemed to have met the utilisation criteria to fly them for six consecutive seasons, at which point they can be used on any other European shorthaul City Pair. The definitions of these are:
"Europe" - The European Union, Iceland, Norway, Switzerland and the Channel Islands
"European Shorthaul City Pair(s)" - Any route connecting London with any other part of Europe (which shall, for the avoidance of doubt, include the Identified UK City Pairs)
In essence, the purpose behind the slots were originally provided to Flybe V1 (tied to Aberdeen, Edinburgh routes, independent carrier with no connection with IAG etc etc) is now no longer relevant. The slots are "owned" by British Airways and released under a Slot Release Agreement to Flybe, and the EU decided (more fool them, but that's now history) that Flybe V1 and V2 were one and the same when it came to operation of the remedy slots.
Only Flybe V2 has the rights to use those slots, so anyone wanting the slots would have to acquire Flybe V2 out of administration. This isn't like the collapse of Monarch or Thomas Cook where they had outright ownership to their slots and those slots could be sold (and were). You didn't have to buy all of Monarch Airlines (in administration) to get the slots, for instance.
If Flybe V2 is bought by an entity which is another airline, but itself ceases to exist, can the rights to use those slots be transferred out of Flybe V2 into that other airline? The answer is that I don't know, and I suspect no-one does until this is tested through legal means. There will be legal opinions flying about but until they are tested, they remain opinions and only that.
The whole thing is, at this point, even more scandalous than it was before. Cyrus Capital took a floating charge over Flybe V2's assets last year, presumably as it put more money into the venture. As a secured creditor, it now stands to realise whatever proceeds can be had from sale of the company in administration and the access to the slots within that. The rest of us get left with the tab for picking up the protective notice awards through the Insolvency Service and so the taxpayer takes a complete shafting for this alongside the poor Flybe V2 employees.