[qual]

I think the "dark forest hypothesis" can apply here.

The advanced alien civilization may indeed be interested in us, but still not consider it their best interest to act as soon as possible.

If they decide to act, other civilizations (perhaps even more advanced) may decide to intervene in some way. A civilization that decides to reach out (in a friendly or hostile way) also reveals their own location in the universe.

The most risk adverse choice is probably to remain quiet, especially if they are millennia ahead of us technologically.

https://en.wikipedia.org/wiki/Dark_forest_hypothesis