Both incidents have been in the first few minutes of flight and this is also a 'long term safety' thing. They're relatively safe to fly still.
On the other hand, if your plane gets stuck in a foreign country the bill just for parking the thing could be massive. Better to get it back while you still can.
Eventually the bill can get so high that it doesn't make financial sense to still attempt to claim to be the owner. As of January there was a McDonnell Douglas MD87 in Madrid thats abandoned. Three 747 were sold for scrap in 2017 after they were abandoned at Kuala Lumpur.
