So the most humane thing is to betray and exile him to an alien world so he can go completely insane.
Or you know, they could try to give him his intelligence and recreate the "Smart Hulk" variant.
Or have Black Bolt, who has trained himself to not speak, not even during his sleep, teach Banner how to keep calm.
Or implant a transporter in his brain so that when he becomes the Hulk it teleports him to a holding pen on the moon, and it can teleport him back to Earth once he revers to Banner.
****, they could even have Betty offer to become a female Hulk in a kind of "Bride of Frankenstein" way to give him peace and keep him out of trouble. That could even be funny.
And that's if you find it impossible that the combined might of Iron Man, Doctor Strange, Mister Fantastic, Professor X, Namor, and Black Bolt cannot cure the Hulk or find a way to help him live with his current state in relative peace.
And if you overlook the fact that those same people don't need to wait for Nick Fury to send Hulk into space to get rid of him. Can't they just teleport him there themselves? He wouldn't get ****ing lost that way.
The least Marvel could have done was have the Hulk do something absolutely atrocious so that the Illuminati has a reason to get rid of Hulk forever - like, oh I don't know... KILL THE AVENGERS?!
Instead of making Scarlet Witch crazy and evil, have the Hulk do the thing everyone's been terrified of him doing. Have him actually, properly, kill the Avengers. Then, you have the Illuminati punish him in this horrific and cruel way (it may be neccessary, but it's cruel). When the Hulk returns, the sides must be taken between those who agree with the Illuminati and those that think there were other options available, because hell, Banner's as much of a victim as the Avengers.
Instead, the Illuminati are self-preserving *******s who are worried he might do something bad and so they banish him forever to Hell... AFTER HE SAVES THE WORLD (Whose side are YOU on? The misunderstood monster who saved the world and was unfairly banished? Or the self-serving pieces of **** who do nothing, claim complete rulership of the planet, and banished a poor misunderstood monster - who just saved the world - for all time because they couldn't be bothered to think of another way to deal with a potential threat? It's a toughy!)
All of which has nothing to do with anything else going on, but is supposed to tie into it all later when they can think of a way to shoehorn the Hulk into the story.
**** it.