The Russian Juniors didn't look very good during the GP season. They were beaten by Alyssa, the Koreans and look beatable by some of the Japanese is my recollection. Anna would be their best hope.
Literally every JGP Russian lady medalled at her assigned event, aside from a 4th from Maia. Tarakanova and Frolova were weaker, but most likely wouldn't be the ones going to Junior Worlds anyway (and if they end up going, that'd be because they showed dramatic improvements). Kamila and Ksenia did not lose to anyone/any non-Russians, and could very well go 1-2 at Junior Worlds. Daria lost to Haein, but has improved drastically. Even Maia debuted a 4S that could very well land her on the team. The juniors do not
need Anna. RusFed would not send Anna back down to juniors
just to beat Alysa, when she has bigger fish to beat in seniors.
Besides, Anna being sent back down to juniors would have zero upside and many downsides. If she wins, umm good for her for beating the juniors? Not very impressive, regardless of how strong Kamila and Alysa are. But if she loses, yikes she was purposefully sent back down to juniors to
win yet still
lost. That would not do her any favors when she inevitably has to go back up to seniors, all the while Sasha and Alena would potentially be winning senior world medals.
Edit: And although RusFed had precedence in sending a lady to both Junior and Senior Worlds (Stasya), Stasya was sent
up from Juniors to Seniors, and not the other way around. She skated on the JGP that season and only skated senior in the CS series (which was common for Russian junior ladies to attend). She performed well at Junior Nationals and was therefore assigned to Junior Worlds. After Zhenya decided not to attend Worlds, Stasya (being next in line based on Nationals rankings) was then sent to Senior Worlds since she was age eligible to go
up.