Okay, this is true, but... the show has changed this a lot, IMO, by having Armand truly hold to the Great Laws, which he didn't really in the book after the Children of Darkness/Satan cult broke up.
Honestly, it took me almost the whole season to wrap my head around the fact that Armand in the show actually holds to these laws. Because it is very different from book!Armand. Armand, in the book, didn't give a shit about the Great Laws at all, really, once the Children of Darkness/Satan coven was disbanded. He used them as an excuse to get rid of Claudia, but that was kind of it.
But in the show, Armand does actually hold to them. We saw that at the end of episode 2x03 when Armand really was going to kill Louis, as confirmed by Assad Zaman. He was going to kill Louis for breaking the Great Laws, the main one being the (attempted) murder of Lestat.
It was only when Armand heard Louis' last request, which was to tell Claudia every day that she's pretty (as Assad confirmed), that Armand couldn't go through with it. Armand already desired Louis by that point, that's a fact; we know that by what Claudia said about Louis and Armand both being attracted to each other, and her feeling that.
But that moment in the tunnel, when he couldn't kill Louis -- and therefore not following the Great Laws -- was the start of his character's internal conflict IMO: Armand's desire for love and acceptance vs his dedication to the coven and the vampire laws that govern them all and coven life.
He loved Louis and wanted Louis from that moment on -- "more than anything in the world," in fact.
So I kinda took that -- Armand on the show actually holding the Great Laws -- as the reason Santiago wasn't killed along with his Maker was because he was given the same choice as Madeleine got during the trial -- join the coven or die. So he did -- Santiago joined the coven instead of choosing death along with his Maker.
And that when someone in a coven makes another vampire against the permission of the Coven Master, that vampire is punished/killed right away, but their fledgling is given the choice to either join the coven (probably in their Maker's place) or be killed as well.
This is a difference, but a BIG one, between the world of the show and the one in the books: there is actually, already, some kind of structure to the vampire "tribe" in the show. Rules and Laws that one is supposed to follow, and they very likely go all the way back to Akasha's time, if you look closely at the (partial) list of the 100 Vampire Laws we see in Episode 2x03. The first 5 being the "Great Laws," and the remaining 95 laws being general laws and rules.
In fact, Law #55 actually gave us a hint of what Louis' punishment would be once his sentence was decreed to be "banishment" instead of death at the trial:
55. Lamia(e) exilia punienda ...buntur in terra tumulanda.
Exiled vampires to be punished ... buried in the ground.
Armand knew that if Louis' sentence was "banishment," what Louis' punishment would be, because it is one of the Laws. Vampires who are exiled, i.e., banished, are buried in the ground.
And, in the theater coven's case, that meant entombed in a box in the underground walls covered in pebbles.
So yeah, I think Santiago's Maker got punished the way he did, but Santiago survived because of the rules laid out regarding such things in the Vampire Laws. Which, in the show, Armand actually holds to, and not just in a convenient way to his own benefit, as in the books.
And, honestly, I can see the method to Rolin and Co. doing this with Armand's character on the show, and the character arc/conflict that is setting up there wrt him.
Particually when it comes to rules 60 through 63 (because all the rules made past the first Great Five are inventions of the show):
60. Vampires nunquam carnalem delectationem cum mortalibus requirent.
Vampires will never seek carnal pleasure with mortals.
61. Vampires nunquam mortalium consortia quaerunt.
Vampires never seek the company of mortals.
62. Vivere inter homines âŠ.nt labentibus annis lamia ad insaniam.
To live among humans âŠ. the passing years ⊠a vampire to madness.
63. Vivere inter homines alios videre senescere ac mori sicut lamia nunquam sequila[?] lamia ad insaniam impellet.
To live among humans and see others grow old and die, like vampires would never, will drive vampires to insanity.
And not only that, but as we saw in the ending with Louis in S2, the Great Laws aren't just something that was part of the COS/TdV's covens -- they are laws that, apparently, govern the wider vampire world at large in the show.
So I can also see this, on the whole, as a pretty significant change to the structure of the vampire world itself in the show overall, which didn't have any governing structure to it at all until the end of the book, Prince Lestat. But, again, the end of Season 2 hints that there is a type of one in place in the form of the Vampire Laws that some of the vampires Louis hears talking about them, and how he's broken them with the publishing of the book.
So, in truth, it isn't just Armand who holds to these laws, but again, the larger vampire world, it seems like.
And, with this change the show has made (and now after I finally finished reading Prince Lestat), I'd bet anything these laws came about and were devised by the Queen's Blood. And will probably play a factor into the aftermath of her defeat at the end of the show's version of Queen of the Damned.