What do we make of it that it was Roger and Peggy who were the duo who ultimately gave SCP it's send-off?
It makes sense, given what the other major characters are doing/how they responded.
Pete was largely not in this episode, Joan was dealing with institutional misogyny, Don began his final journey, Cooper has been dead, same with Pryce, Ted Caugh has happy been absorbed into McCann (check out the symbolism with him just in the white shirt and tie vs Don in the suit), Sally has already been put on a bus, Megan went back to LA, and Betty was reading in her kitchen (but none of them were ever really involved with SC&P).
That leaves Roger and Peggy. Roger makes a lot of sense, his father founded the original Sterling Cooper. Other than his time in the Navy, Sterling Cooper (and later SCDP and SC&P) was his life and destiny. To see it rolled up and consumed has to cause him to ache (and drink).
Peggy also makes a lot of sense. She pulled herself up from one of the most damning things that could happen to a young lady of that time (a child out of wedlock), fought against misogyny and showed all of her bosses that she means business. That the world described to her isn't enough, so she will make her own way. Roger reminds her to be herself, hence the awesome entrance. It gives us, the viewer, that despite her having to deal with everything Joan is dealing with, Peggy will be fine.