Guild Wars 2

And that’s because they are Mursaat and actually former Kralkatorrik minions, same as Glint, and thus they know how to hatch it?

They probably don’t like us and will help only because the other Elder Dragon is threatening them and they need our help too.

Mordremoth -> Sylvari / Kralkatorrik -> Mursaat

There is no information (or even hints) that the Mursaat are (former) minions of any of the Elder Dragons.

In any case, is it likely that they will be important to hatch the egg? Given that Caithe was keeping it close to that golden door in the cave. Which is somewhat confusing giving that the Forgotten are also in on this.

it’s never stated that anyone is in on anything

The Mursaat are not minions of elder dragons. They are ancient enemies of the dragons that allied with other old races to try to fight them. Though they then ran away and abandoned their allies.

Testudo.4620:

it’s never stated that anyone is in on anything

in…volved.