Because I am now aware that they would like to know. That is why. Otherwise, I definitely would not.
Thanks for everyone's input. I agree that keeping it to myself is the best choice unless I can be sure they would want to know. I have received a message that if it were them- they would want to know.
And like you say, I could be wrong, and they are under no obligation to confirm or deny. Totally up to them. Doesn't matter to me whatsoever whether they confirm or deny, but now I can continue reading and contributing with full transparency (to this specific poster). Which does make me feel better.