They're likely taking more from the plot of USUM than SM by this point, especially since from what we can tell Lusamine's a lot more subdued in the former.

The anime is weird, cause it fills in some details while creating all new ones. Most everyone assumed Lusamine became obsessed with nihilego due to her own research after the lose of her husband, but the anime seems to imply Faba is the one who Brought it to Aether paradise (what with him being in that flashback), Faba is also shown in the lineup of Team Rainbow Rocket members in the Japanese trailer released recently.