So working on the Paxton Rall achievement, and the last place I need to see him is Zakuul. However it's not a normal planet I can travel to, as I'm still early in my story.

Does anyone know if I could be summoned there by a guildmate who has access, and would doing so affect my story at all?

I know that you can hit planets later in the storyline as long as you don't do the quests there and it won't break anything. But I don't know how Zakuul works specifically.