Alma 19:7

therefore, what the queen desired of him, was his only desire. Therefore he went in to see the king, according as the queen had desired him; and he saw the king, and he knew that he was not dead.

What the queen wanted was the only thing he wanted. So he went in to see the king. This is what the queen had wanted him to do. He saw the king. He knew that he was not dead.

So what the queen wanted was exactly what Ammon wanted too. He went to see the king, just as the queen had asked. When he saw Lamoni, he knew he wasn't dead.