catch and carry

[kkid091]

Question is on catch and carry on out of play line.
Runner on second, 1 out, ball hit to out of play line by first base, first baseman makes a catch, either with both feet in play steps out with one foot, pivots and comes back into play. Ruling? Or he is straddeling the out of play line, and pivots back into play after the catch. Ruling? In both cases his one foot always was in play. The initial ruling was the plate umpire said no catch and gave the runner at second 2 bases to score the winning run. Then changed his mind, ruled a catch, and gave the runner at second third. Is this right?