Then why send Rob to Ultramar?
Supposedly, according to 'The Board is Set' we have some speculation as the Emp and Malc apparently spent the Heresy playing through scenarios for the Crusade and the Heresy in their spare time, seemingly trying to piece together where they messed up, where things could have gone better and using their powers to sort of 'what if?'.
The implication was that the Emp could only 'save' 9 Primarchs and that something about the missing two made them useless to both the Emp and Chaos (can't imagine what made them that messed up aside from the known case regarding a gene-issue).
They actually talk about swapping control of several and even the Emp managing to pull a fast one once or twice (he is mentioned to have swapped Chemos and Chogoris for one thing).
The thing is that we know from another story that the Emp and Malc had this special artifact that let them scry across the Galaxy and from another that the Emp developed an extensive knowledge during or after the DAoT of other planets. As well as the Emp having faulty but potent precognition according to MoM.
We also know from both Massacre and Inferno that he did prioritize retrieving planets like Medusa and Fenris ASAP. Added to that is the fact that we know Baal is in a tough spot to reach usually and a pattern forms. Added to this is that we know Russ was actually against using Fenris as a base for a Legion and only committed due to the Emp pushing for it. Other examples like Caliban and Tizca seem more or less uncannily structured to feed Legions.
I genuinely think he sort of earmarked a number of worlds for the Legions from the beginning and when Chaos nabbed the Primarchs, he tried to throw as many as he could to their ear-marked planets. Heck, Erdu does seem to genuinely love her 'sons' too so I dont think she would have pushed against him here either.
So... Robbie-G was probably always meant to link up with Ultramar and when Chaos nabbed them I think the Emp steered him there and did so with as many as he could manage.
Thats theory-crafting from a few short-stories, some lines from the BBs and what we know about the capacities of various actors though, so while not the weakest theory it is just a theory.
Edited by StrangerOrders, 10 October 2020 - 12:37 AM.