How he ingested the Geneseed was oddly familiar to how the the Deamon prince did it in Storm of Iron book! Otherwise, it would be an interesting turn to see him defend the emperor.

SPOILERS:

Both Arik Taranis and Ghota ,
(thanks to Arik's well equiped gene lab) were able to replicate brand new Progenoid Glands from an intact sample and successfully implant them into their failing bodies. I suppose those two still have a card to play within the lore, be it HH or The End Times (defending the Emperor's Golden Throne alongside his trusted lieutenant - maybe...). Hell, GW didn't even allow Fabius Bile to be killed in the novels of writer James Swallow (41st mill. setting), so rest assured we'll be hearing of the Proto Astartes's exploits in the future.



END of SPOILERS.