I'd say the best thing that can happen is the stealth route. It gets us to the moon while leaving the fire giants there to encounter the demons and their next victim when they arrive. Or, if they follow us into the jungle, they'll draw attention away from us due to their size and numbers.
If Apex discovers that stealth won't work, we can present ourselves as a group of Pathfinders who are willing to engage in a joint expedition to what lies beyond. We can offer to help with activating the portal that (we can assume) has stumped them. That way, there's really no room for them to betray us before we have a chance to slip through the portal and leave them to encounter the demons or draw attention away from us.