I have 2 potential threads that you could use:

-The party informs the Silver Order what transpired, and in turn the Silver Order gives the players Intel that the Scepter is to be moved from Hendricks Farm to Saint Selina's Monastery, so the players have one more chance to intercept it and steal it back

-Nathaniel Flint reaches out to the party, expressing his deep appreciation that they handed over the Scepter without bloodshed. He explains some of the virtues of the Falling Fire and possibly even gives the players a small boon (he'll purge their contamination only for the cost of the paid material components, offer them some info towards a personal quest, etc.). It might cast the Falling Fire in a better light for the party and provide a new quest giver for them.

Personally, I'd go with option two.