Yes, obviously he could have, but he was unwilling to just come out and admit to his reasons for wanting to keep it from them. Ford was too kind and polite to want to say anything uncharitable about his siblings (at least while they were out of the room; sometimes he did so to their face with very little problem), and there was no charitable way to say yes, I could have, but it wouldn't have helped matters because they're both nervous wrecks.

He shrugged instead, pretending indifference. "They have plenty of time to change. I promise Mr. Lestrange won't be put out." He glanced at Noble, then added under his breath, "Even if Grace doesn't talk to him, probably."