The Shaman of Songs was friendly and happy, most of the time. And she enjoyed sharing her Na'Vi culture and spirituality with tourists when encountered.
Just because she was reclusive, didn't mean she was a grouchy hermit. She simply preferred the company of the beings on the Kaspavan River - sacred to the Na'Vi. The peace and tranquillity allowed her to focus on her own spirituality.
So, when the boats full of tourists passed by - and there were probably thousands, not that she actually counted - she sang her song for them, praising Eywa.
It wasn't something she was doing out of any obligation to Alpha Centauri Expeditions. However, as she was working with them to promote the culture of the Na'Vi, this was absolutely something she wanted to do. Something she chose to do.
More importantly, it was something she enjoyed.
And she believed this cross-cultural exchange would help foster understanding.
The Na'Vi River Journey is a weird ride. The Shaman of Songs is the only animatronic in the ride and she appears at the end. It's quite an anti-climax, especially when you've been waiting over an hour and that's in the FastPass line, because it's like five minutes long and you're just kinda staring at screens and lights supposed to be bioluminescence and then there's one animatronic and it's time to unload?
Like wow.
It's like they blew all the budget on that one animatronic. But it is a very impressive animatronic. That is, when it works.
And the song's kinda fun too.