They know about goblins roaming the area, they don't know about how big the cult is, or the leaders.
They would if Aradin's group escaped and managed to tell the others. You know... After he made a distraction for them.
And even if he frees himself and waits until you leave with Minthara and teh forces, it is still a stupid plan. He could have been killed beforehand. He is entirely relying on Tav to free him or thin out the forces however.
Better than sitting in the Grove doing nothing while waiting for the Goblins to come and massacre everyone.
Also, he's not relying on Tav to free him or thin the forces out. The goblins would naturally thin themselves out as they either found the Grove and started an attack, or found some other place to raid.
To say nothing about, yes, he comes into action when Tav frees him. Doesn't mean he's not working on a plan to do something himself (Sure, whatever he does come up with fails if we account for sequence breaking by going to Mountain Pass early but that doesn't mean he was completely reliant on Tav)
I get, that you like the character
I actually don't. I hate the character.
But his situation regarding the goblins is not proof that he's some sort of imbecile.
