According to Mark Henn, lead animator on Frozen, Olaf's love isn't true love, but rather a "naïve, childlike love and affection".
Henn: Oh, well, there are a lot of things. It's not always very obvious in the stories, but I think whether it's obvious or not, I
think one of the aspects is the whole notion of the different types of
love that are demonstrated, are portrayed in the film. You have a
variety of types of love shown from Olaf, very naïve, childlike love
and affection, to Anna's very reactionary, very seemingly true love,
but it's a bit shallow when she meets Hans.
As such, his love isn't the right kind of love to break such a serious curse.
This is backed up in a conversation with the producers
If Elsa could still create Olaf, maybe the loving sister she once knew
is still there. He represents a child-like innocent love and animators
gave him toddler-like qualities (outstretched arms and the way he
moves) to enhance the theme.
A conversation with the Directors
“In ‘Let It Go,’ the first thing she does is the last thing they did,
in terms of the last time she was happy,” Lee said. “Like, they built
this snowman, not magical, but together—and that was her happiest
moment with Anna. And then everything went bad. So when she starts
‘Let It Go,’ she goes right back to the last moment she was happy. And
it was Olaf. So to us, he’s imbued with the magic of innocent love, of
love that’s pure, that’s undamaged and unhurt by life.”
An interview with the film's Producer
That song gave us the theme of the movie, which was 'love versus
fear,' where Elsa is ruled by fear, and Anna is positive and believes
in everyone, believes in herself and doesn't let anything get in her
way... We ended up rewriting that entire movie so that every character
would reflect that theme. So Olaf represents innocent love, Hans
represents that love at first sight, there's true love's kiss, and
Kristoff represents that love that develops over time once you get to
And with the best will in the world, Olaf isn't a family member, at least according to the Directors
Jenn: It all leads to the greatest of all [love] which is family. We
liked having the parallel stories that combine at the end, because I
think that's sort of what it all ends up being.