Sporting announced yesterday that United have informed them of plans to meet the €10m buyout clause in Amorim's contract.
"(Amorim's) attitude and personality seemed to be one thing, but it fell apart from one moment to the next. His love, passion and devotion for Sporting were just fantasy situations," Soares told Radio Renascenca.
"He was the one who created an environment with a whole nation of fanatics around him, who loved and respected him. He shouldn't have spat in the plate that gave him his soup. I am a fan of Rúben Amorim, but there are things that should not be allowed. It was in Sporting that he made his name."
Soares believes that Amorim could have handled the situation better.
"If he had not let himself get caught up in the dream of making millions, and because he was loved by Sporting's fans, he should have thought of going through the big door and not in this way. Sporting fans will surely react."