Don't get in his way and he'll kill the Wither for you

Wither: No, You can't(In open area)
Warden: No, I can(In an artificial cave)

Not the warden!

They are highly dangerous and terrifying, but they can be useful

But then you need to deal with the Warden; an arguably harder thing to deal with.

Just stay away from them until they despawn, then you can get the Nether Star

True, but there's a chance that they'll smell your gamer scent since you'll most likely be within proximity, and the wardens intense sniff's range of around 20 blocks.

Jesus Christ