Perhaps not. It's only a matter of time- when there's a loss of a Harbinger, everyone ends up knowing about it sooner or later. It's not exactly something that can be easily hidden, especially given that he was the Sixth.

[With all the structure changes and having to reassign swaths of troops to new Harbingers, everyone talks. Childe isn't going to pretend like this is classified information.]

That being said...said former Harbinger is here with us in Nightwake City. I would be an irresponsible comrade not to tell you about it, though I have no reason to suspect that he's got any plans that we have to worry about.

[Just Dottore, if he ever shows up...]