if bankrupty - the tracks and etc would be left there but that's why its very odd
Looks like it is.
When bankrupcy happens everything except road will be removed. The road will be marked with 'without owner' and everyone can delete it.
If you have a public station or public aircraft parking, the tracks/taxiway below it will also become 'without owner' and everyone can connect their tracks/taxiway into it.
After going bankrupt and a year is passed before everything is removed and the company is reseted.