Mac is able to call Harry for help, also (Heorot). If Mac has been around for millenia, it seems he's likely to know who took Elizabeth (was that her name?), and how dangerous it would be for Harry to face the Grendelkin (although assuming he knew all that, it's likely he knew Sigrun would be involved so Harry wouldn't be going in alone). Involving himself as he did there (by getting Harry involved) seems sort of non-neutral to me.
(Just tossing this out there - I don't have an opinion on Mac either way.)
Pretending neutrality when one actually isn't neutral isn't exactly a new covert tactic.
Some of what's been quoted before is relevant to a slightly different angle on things.
Eldest Gruff said:
Mac is there, at someone's behest or his own, to 'look in' on Harry so to speak. How he does or does not handle him is partly up to his discretion I imagine but also at least somewhat beholden to whatever nature he is or turns out to be and the choices that came of it.
Not necessarily wrong, per se, just possibly a bit underestimating.
From DB we know,
He'd opened the tavern a few years before I'd moved to Chicago.
This is either pure happenstance (accident) or Mac is there purposefully.
When Vadderung (Kringle) says,
If one wishes to alter the course of history, it's a far simpler matter to attempt to shape the future.
he might be giving a very big clue that's being totally missed (by Harry and all of us).
Harry's disturbed by Vadderung's knowledge saying,
Oh, man. Vadderung knew about Ebenezar. Which meant that either he was higher in the old man's circle of trust than I was, or he had access to an astoundingly scary pool of information.
Though it's probably both, as Odin, we know he's definitely got 'an astoundingly scary pool of information'. That's one of Odin's hallmark traits - foreknowledge.
I think it just as likely that, in addition to the favored Tam Lin/Gregori/Transbstantiated Raphael trio, Mac could possibly be a seperate agent placed for the purpose of doing what Odin/Kringle has proposed -- shape the future by starting far enough in the past to get that job done without alerting many figures of power to the manipulation. JB has indicated that creating a Starborn involves a complex set of events. There's nothing in that phrase that specifies that all those events have to occur before that Starborn's birth. He's also indicated that Elaine is (or at least has been) a potential Starborn. Meaning either pre-birth circumstances should have mirrored Harry's in some way and we've little to go on that supports that. So, by implication it seems that "Starborn" might be an on going process... a destination not a starting point.