Surely they'll sell it to the scrappers who'll give them the most for it (or charge them the least for disposal), scrapping parts for the sake of it doesn't make sense.
I agree it doesn't make sense but there quite a few things that don't on that project.
There are massive political issues surrounding this ship.
When she is refloated she will be scrapped in a suitable location in Italy. Also Costa and Carnival will not want people bringing up her name regarding components from her being used on other ships.
One of the problems is finding somewhere big enough to take her, she was pretty big ship when operation, there will be huge sponsons stuck on both sides, so it will be difficult to find a dry dock where it will fit.
Anyway fair play to Titan Salvage, both Smit and Mammoet, the big Dutch companies said it was going to fail but Titan have pulled off some pretty impressive engineering.