But he didn't. 20/20 hindsight is a wonderful thing, and had Vitelli seen in the future and known his daughter would die as a result of this marriage, he probably would not have allowed Michael to meet and marry her, and gladly have given his life to prevent it, as Michael implies might happen.

As it turns out, Michael presents himself in a respectable manner, and maybe Vitelli did see possible personal gain in a marriage between his and the Corleone family. Also, Appolonia and Michael were clearly in love, and he saw his daughter would be happy with this young man.

So no, I do not think he made a careless decision.

Apple