Is someone who has rescinded his/her SSN eligible for any government benefits?
No. If you want government benefits, something not provided for in the Constitution, then you must become a federal citizen and waive your unalienable rights.
If you want to live free, then you must give up your eligibility for government benefits.
You can obtain comparable benefits from the private sector, but not from the government. Remember that in order for the government to pay you a benefit, it must take that money from someone else, someone who may be less well off than you. Government-sponsored benefits are fundamentally immoral and unconstitutional. If you value your freedom, you must give up your eligibility for government benefits.