After what K/A pulled with Anna and Sergei, I`m not sure that I want I/Z to stay with Kustarova. I know that we haven`t heard yet Sergei`s side of the story, but is the way they behaved so much different to what Nikita/Morozov did 2 years ago?
IMO, what I/Z need is a training environment, where they can prepare peacefully and I see that rather happening in Novi. K/A seem to be rather focussed on saving their school whatever maybe the costs.
I've read an insider who knows IZ say at a Russian forum that Mozgov just said it was the coaches' initiative to cover himself, and this seems very likely to me. Firstly, Mozgov has a history of frequently changing partners, often for trivial or made-up reasons (he'd had 4 partners before Yanovskaya, so Popova will be his 6th.) Secondly, Mozgov and Popova were trying out on Popova's rink, not in Medvedkovo, and Popova's coach was livid when they announced that they would be skating with KA, posting an extremely rude post on her social media account. Clearly, it was Mozgov's initiative, and he and Popova must have told her coach or at the very least insinuated that they'd be training with her. Thirdly, why on earth would AK want to split a team that had been together for 4 years for the sake of pairing Mozgov with a girl who was 4th at Jr GPF and 6th at Jr Worlds?
It seems to me that Mozgov was disappointed with how his first season in seniors had panned out and decided to change his partner, yet again, hoping that he'd look better with the passionate Popova. Maybe the example of Zhiganshin who clearly looks better with Ilinykh than with Sinitsina inspired him. But Mozgov must have realized that his coaches wouldn't approve the idea of wasting 4 years worth of work for the sake of a 4-6th place finisher in Jr. So he first tried skating with Popova at her rink, letting her coach Rumyantseva think that they'd train with her if they decide to become a team. Both Rumyantseva and Popova must have been happy with this idea because Mozgov is a more successful and higher-ranking skater (similar to Sinitsina's reasons for splitting her partnership with Zhiganshin to team up with Katsalapov). But once Mozgov decided that Popova would suit him, he must have gone back to his coaches and dropped the bombshell on them that he's splitting with Yanovskaya and pairing up with Popova and wants them to coach him and Popova. Why? Clearly, he thinks that KA are better coaches who'll make him and Popova look well together quickly (like with IZ); plus, AK have more of a name than Rumyantseva. Naturally, this about-face must have made Rumyantseva very angry (not that it excuses her post IMO). And what could AK have done in this situation? I think no more than when Sinitsina decided to skate with Katsalapov, except that Mozgov and Popova wanted to train with them. AK may have tried to reason with Mozgov, but if so, obviously to no avail: he must have already made a decision. They could, of course, refuse to train him and Popova and be left with hadrly anybody on a permanent basis, but what coach would do that and whom would it help? AK having been in the dark till the last moment would also explain why they hadn't let Yanovskaya know ahead of time, so that she could look for a new partner as well.
My guess is that Mozgov's new partnership will prove to be no more long-lasting than his previous ones, and that consequently he's not likely to achieve great success in sport. So I hope that AK are wasting no time in looking for a new partner for Yanovskaya, just as they didn't waste any time when Sinitsina had left Zhiganshin and immediately began looking for a new partner for him (he said he was surprised by how quickly it was all arranged). TBH, I personally like neither Mozgov nor Yanovskaya nor Popova - I find all three of them rather vulgar, but I think that Yanovskaya is more likely to achieve success with a different partner than Mozgov with Popova, because she seems to be more level-headed and more likely to stick with her new partner. For AK's sake I hope she'll find a compatible partner soon. Maybe she'll even look more classy with a different partner, who knows?