Theo went through the ritual as a child, they mentioned they did it when his mom died, because they didnยดt know if he was bitten or not.
So doing it for Cal just opened him up and made him recall some repressed memories.
Margo does get it.
She is now the keeper.
They just canยดt celebrate it publicly because... you know
"Husband ate grandma" might not be a great story to tell the entire legacy community.
And Elinor is the keeper in waiting now, the next in line.
Which is why Margo gave Elinor the gift, as thatยดs the tradition.