Looks like Podesta wrote that email in February of 2015 (see the date in your graphic). My understanding is that the Podesta emails were hacked around March of 2016. Thus I don’t think it plausible Podesta was referring to the hacking of his emails, rather he must have meant some other kind of leak. Seth Rich was killed in July of 2016, and while it is quite possible that he was killed in retaliation for the Podesta email leak, Podesta’s comment here does not seem to be related to it.
It’s the seriousness of the charge—not the relevant facts that count—what’s sauce for the goose is sauce for the gander!
Perhaps not specifically, but it reveals how he operates.