He moved to the US when he was a Light Heavyweight in persue of big money fights. He fought for the WBC LHW championship on a Don King card. He wanted to fight against the biggest names. At that time the biggest names at LHW were Bernard Hopkins who was coming off wins against DeLaHoya and Eastman. RJJ was coming off a string of loses but was still a big name. Jermain Taylor was becoming a star, all Americans. After his loss to Chad Dawson and inability to make 175lb limit he moved up to CW division where again the champions were Americans, Cunningham, O'neal Bell, Johnatan BAnks ect. So by the time he moved up to HW division he was already living in NJ for years so it doesnt make any sense for him to move to Europe and search for fights over there.
got his ass whupped by Cunningham and Chambers and journeyman Walker put him on his ass, terrible year for him. Also lets not forget Dawson schooled his ass as well...... dude should have 3 L's to Americans- the rulers of boxing.