The context of this statement is important. Pa is addressing the issue of burying Granpa. The family cannot afford to bury him properly and they also do not want to put him in a pauper's grave. This indignity is something they are not yet ready to suffer.
In order to bury the man, the family will need to break the law as it is illegal to bury someone without certain permits and permissions.
The act is one of plain dignity - to bury Granpa - and one of moral necessity. The law here becomes immoral.
Many would argue that following an immoral law constitutes an immoral act. Is it subversive or transgressive to bury a man? No one will be hurt by this act. The family patiently discusses the act before undertaking it. This is a measured, rational behavior in the face of difficult circumstances.
We might argue that the family shows the ability to reasonably navigate a social system. They do not break any moral codes, nor do they act rashly or dangerously.