Take a look at the situation:
The Vitlings are warriors who attack anyone they see BUT they obviously were willing to talk to the winter wolves in order to set up the pact against the Cold Ones.
The Vitlings are warriors BUT they need the winter wolves to protect them against the Cold Ones.
The Vitlings attack stangers on sight BUT the one Vitling they met could speak to the party with a common language.
Conclusion: Probably the reputation of the Vitlings is a bit off from the reality.
Next:
The Winter Wolves protect the Vitlings from the Cold Ones, in exchange for the occasional tasty tot.
The Vitlings cannot protect themselves from the Cold Ones.
Conclusion: Either the Cold Ones don't exist (could well be the Winter Wolves themselves, no?) OR the Cold Ones are pretty powerful.
In either case, the winter wolves preferred dealing with the Vitlings to simply attacking the Vitlings and taking what they wanted. Moreover, it is quite possible that, with the Cold Ones to think about, the winter wolves would prefer not to be fighting on two fronts.
There is a lot of weasel-room in here for the PCs to enter into the mix, figure out what's going on, and deal with it accordingly. The Vitlings might make strong allies in finding the buried gnome city....at least in terms of supplies. And, if the party acts as "missionaries" to the Vitlings, the Church is going to be very pleased with them, right?
There are lots of reasons to believe that the situation is open to investigation. There are lots of reasons to investigate, assuming that the characters are good-aligned. There are good reasons to investigate even if they are not. After all, leaving the kid won't stop the pack from hunting them down later, will it? And, if they are going to continue traveling north, wouldn't they want to know more about these Cold Ones?
I would.
RC