You’re measuring the value, not setting it. Just like looking at a ball that was wrapped in a bag, seeing that it is red means your partner must therefore have

You’re measuring the value, not setting it. Just like looking at a ball that was wrapped in a bag, seeing that it is red means your partner must therefore have picked the blue ball, but there’s no way you can control whether your partner had the red or blue ball, so the two of you can’t use that information to communicate FTL.