Misdemeanor=Felony under U.S Law?

My brother-in-law applied for citizenship in the U.S in Georgia after living here for 16 years, worked, had a social security card etc...He married my sister in 2005, and they were told that his citizenship could not be approved because he had a assault misdemeanor on his record in Georgia, it was a from a girlfriend in the past in 1993, with no other record just the one charge. He was not deported, but a attorney said that he would now be put in the deportation process because he overstayed his visitor visa and could be sentenced to jail, in the removal process, so my brother-in-law and sister went home to his native country Grenada, and found it to not be like home, so my question is, what would be the right process for him to come home, to the United States, he was not deported, he is married to my sister a U.S Citizen, his children are U.S. Citizen's, He payed taxes for 16 years, had one bad situation with a girlfriend 14 years ago... Can he just come back and work, and just forget the citizenship, or what should he do? He was trying to do the right thing.. Can he just apply for a new Visitor Visa? or Work Visa if he has a sponsor? It is really hard on my sister, she has to travel back and forth, and they are not wealthy, he can not even see his children or help take care of them here, without work? Any suggestions ?

see your other post