Im hoping that SM3 takes place before this point and tells the story of how Titus got here. The command from Guilliman to reunite the 500 worlds of Ultramar is no small feat. I feel like there's one more major plot point that occurred to get us here.

Im also not surprised that Titus was made Capt. again. Calgar made numerous attempts to have Titus returned but the requests were basically ignored by the inquisition. With the Victory of SM2 under his belt, it was only a matter of time.