Your implied standpoint is that it’s only worth preserving if you can engage with it. Imagine having the same attitude towards endangered animals “why should we preserve the giant turtles when I can’t even find a shop that will sell me one?”
The language is intimately tied to the people and the culture. It’s not like they want to push random people around the world to learn it just for a laugh.
You're making assumptions about my implications and comparing two completely different things.
A well archived language can be reborn again - a dead species can't (yet).
Furthermore, where are you taking that I'm advocating forcefully spreading a language?
I'm stating a two very simple facts:
1. If you want a language to stay alive, you need speakers.
2. If you want a language to outlive speakers, you need to archive it well.
Since we live in a world of choice, you'll have to do something in order to let people choose to become a speaker of that language.
The language is intimately tied to the people and the culture. It’s not like they want to push random people around the world to learn it just for a laugh.