BHO Sr. was not a resident alien. He was a visitor, here on a student visa. A resident alien is someone who intends to stay, even if they eventually don't. Some on student visas do stay, but they have to convert to legal resdient alien status first. After a while they can, and most do, apply for citizenship.
BHO Sr. always intended to trot back to Kenya, which he did, taking a different American back to become his third wife, (if you count Stanley Ann) while he was still married to the first and second (S.A.) All perfectly legal, in Kenya.
Then I stand corrected.