That's exactly it. This floated around newsrooms before, and parts of these allegations have peaked at times, but that this has been verified to be included in the official briefing is significant.
Whether these allegations are true is another matter. However it is also worth considering the following @BadSport
The FBI had investigations on both these allegations, and the dickhead Wiener's laptop.
The FBI chose to publicly issue a statement on one of these, and not the other
The one they did issue a statement on they had to come out later saying 'my bad'
The one they issued no statement is damning, even if only a fraction is true (and given what we know and is independantly verified from before, a fraction is most certainly true)
This almost certainly had a material impact on the election, given the tight margins in a few states
Oh, and the PeeOTUS? He is having a meltdown over the story. Not the behavior of an innocent man, for damn sure.
So tell me again why Comey needed to say anything about Clinton?