No cookie for them!
A few people corrected the number of RHD in their comments (namely Liquidformat and Thurbane), so it's hard to say whether all the commenters considered 6 or 8 RHD. And even then, Thurbane deemed it a borderline +0 with 8 RHD, lord_khaine voted +1 with 6 and Liquidformat only said it was -0 with 6 RHD by comparing it to a permanently enlarged Water Orc with multiclass penalties between barbarian and warblade. I understand there's a big opportunity cost to 6 RHD, but I feel -0 with 6 RHD is a little bit insincere (I admit I didn't read the original discussion for this one since it was so similar to Hill, but it's actually conforting me in my rating.).
Yes, that seems to be it. FF really is a unique book, with its hybrid rules between 3.0 and 3.5. Speaking of which, ...
I was myself a bit confused here. I was looking at the 3.0 version of (Improved) Whirlwind Attack. In 3.0, the regular WA only allowed you to attack adjacent opponents, while IWA allowed you to attack your whole reach as a full round action (which is what the Blood Golem can do). IWA was then errataed after 3.5 released to only cost a standard action, then was reprinted in Dragon 343, which is the version you linked. I wonder if the golem saying it "can attack its whole reach as if using Whirlwind Attack" was supposed to be teasing the new version of Whirlwind Attack for 3.5, or if it was just an editing error.
Oh, I get the purpose, I'm just amused by the form "it does these evil things that require feelings, even though it is mindless". Okay. How ? Does it take actions on its own ? How do we know it is satisfied of killing things ? In that case, like with the Knell Beetle, just give them intelligence if you want them to be intelligent, or at least enough Charisma to have emotions. It is imbued with the spirit of Hextor and the suffering of the sacrificial victims, I get that. Then make it show mechanically. The Waker's Law exists for a reason.
A golem made of illithid anything is something to be taken seriously, because it means there's an illithid nearby !
More seriously, it's more something like an extension of an elder brain. There's always a bit of an elder brain at the center of a brain golem, and that elder brain can control and see through the golem as if it were here (in 2e edition lore, at least). After its purpose has been completed, the brain golem goes back and is absorbed back inside its progenitor. So it's both a calzone golem kept in the freezer for later, a flesh golem for brain-composed creature, and the poor man's Magic Jar.