A ship would have disturbed

“This is monstrous,” said Lady Nym. “I would not have believed it, not of a Kingsguard knight.”
“They are sworn to obey, just as my captain is,” the prince said. “I had my doubts as well, but you all saw how Ser Balon balked when I suggested that we go by sea. A ship would have disturbed all the queen’s arrangements.” (A Dance with Dragons, novel)

Context: Sand Snakes were bastard daughters of Prince Oberyn, and Prince Doran. Tyene, Obara and Lady Nym were the three of Sand Snakes. Prince Oberyn was Doran’s brother. Prince Doran just told them that Queen Cersei asked Ser Balon, who was a Kingsuard Knight, to escort her daughter and Prince Doran’s son to the capital. If they go overland, they will be attacked by barbarians and the son would die. This is a trap set up by the Queen. But if they go by sea, the Queen’s scheme to murder the son won’t be successful.

I know the second “would have” implies “If they had travelled by ship the Queen’s plan to murder the son would not have worked”
So for the underlined sentence, do both if clause and the would have clause refer to the future, which is not going to happen or is counterfactual?

Thank you.