The point of having a sponsor is to prove that the visa holder will not become a public charge in the United States.  In other words, the sponsor requirement is in place to help insure that the the visa holder will not need government assistance from social programs such as welfare.  Technically, a government agency that pays money to the visa holder could hold the sponsor responible to repay any government assistance rendered to the visa holder.Other than the financial responsibility, I am not aware of any other obligations the sponsor has to the visa holder.  I do not believe the sponsor has a duty to insure the visa holder maintains his immigration status.