Remember that the PC who knows this stuff also has much more at stake and likely a much lower margin of error...

There are always secrets that some will kill to keep...

And the Court knows the PC could share those secrets, so they'd better watch their mouth. And if the other PCs learn too much, it's a fair bet that they've been talking...

In short, while the PC knows more, there can also be story reasons why it isn't in the PC's best interest to blab. Then the PC does have the choice to do so, but they and the party have to face the consequences.