Regarding Magik vs. MotherMold, and not being in on the space mission...
I'm not certain that Magik is in HoX/PoX.
The Illyana 2.0 of 616 might be a rare event, abducted and reanimated by Belasco in a very few of all possible worlds, perhaps only in one of Moira's lives.
She's shown in Phoenix Five form in the "Lost Decade" of Life 4, but in none of the others that I can see.
Rasputin of Life 9 having a SoulSword is suggestive, but we don't have details.
If our 616 timeline was actually Life 4, or the Life 6 not shown in HoX #2, then the events of Life 10 detailed in HoX/PoX might be a world free of Illyana 2.0, filled mostly with pod-mutants founded on a separate peace Xavier negotiated with Krakoa in an alternative version of Deadly Genesis.
Perhaps that means that worlds with Illyana 2.0 in them are damned, and that Moira made sure subsequent lives were Magik-less, perhaps by preventing young Illyana from going to Cthulhu Island to be abducted by Belasco, or maybe preventing her from even being kidnapped by Arcade in the first place.
Also recall that Nimrod first entered our 616 timeline by being drawn here by Illyana 1.0 when she eliminated Kulan Gath's existence through a "TemporalSpacial Claudication", back in UXM v1 #191.
Eliminate Magik, delay Nimrod might be Moira's reasoning.
(On the other hand the 616 might be Life 11, and Moira's death by Legacy was her Final Death, mostly but not quite repeating Life 4 with Magik.)