People that have just declared bankruptcy get a huge amount of credit card offers, for two reasons:
1) People who mismanage their money are credit card companies' bread and butter. Very financially responsible people - those who pay their credit card balance in full every month - are actually labled "deadbeats" by the credit card industry because every month they are extended up to a month of credit for free (other than small fees that merchants pay).
People who keep high balances with outrageous interest, on the other hand, are pure profit centers. This is the kind of customer that the credit card companies hope someone fresh out of bankruptcy will become.
2) After someone declares Chapter 7 bankruptcy it usually cannot be declared by them again for seven years, so there is almost no risk that someone fresh out of bankruptcy will be able to declare bankruptcy.