The Laughing God said:
I haven't finished reading Dead Stars yet, but one vitally important piece of information seems to be what the Hag told him (p8):
His family found the means [to travel in time, I guess] long ago but failed to understand what it was. At Tanis, his bloodline had even captured the memory of its radiance but remained ignorant of its truth and power, and by their misunderstood lore he had used its shadow and echo in his devices without understanding their full implications. His answer lay in that thing which mankind called Komus, the Tyrant Star.
This cute little piece of writing is purposefully vague (memory of radiance? its shadow and echo without being clear what 'it' refers to?), but the reference to Tanis is very intrigueing. What the hell really happened there? Radiance may refer to Komus, who shines black.
As far as what Haarlock is doing in the Tyrant Star (as that does seem to be what had happened to him, he was in the star, whatever that means) I thought the implication was that he was waiting for something. Something in the distant future could bring about his master plan (or more likely some perverted form of it) but even with Imperial medical technology he would not live long enough (and he wanted to avoid some of the other possibilities like Halo Devices... probably he knows what they do to people) so by staying "within" the Tyrant Star he has some way of passing by the centuries until whatever it is he is after becomes available.
As far as Immediate consequences of the release of Haarlock goes: I would say none. Part of the point of both results is that the consequences are a long distance in the future (the events seen while wandering through the Tesseract). And seeing as the default position is probably to prevent his return 9due to the build up the series presenting him as an enemy) you are probably not wanting them to be further discouraged from doing so. As far as The Inquisition is concerned: How are they to know? If the acolytes report failure then yes, maybe punishment ensues, but they are the only ones there to tell them what happens, and I doubt Haarlock immediately announces his return to the Calixisis Sector. He almost certainly disappears for a while to build up his strength and put his long established plans into action. At that point he will return as the big threat, but probably not for years, if not decades, of in game time.