No.
Dual Handed Assault uses both of your hands during the Strike. When you're using Well-Armed, you don't have two hands. Juggling doesn't change that. It may count as your only hand being free if your other arm (with weapon) is the only thing you're juggling, but not having two hands to make the 2-handed Strike with is definitely a more specific condition than juggling.
Technically, the only requirements of dual handed strike are "You are wielding a one-handed melee weapon and have a free hand" both of which Juggle lets you qualify for.
You run into some glitches with the flavor and mechanics text, but at no point do you fail to meet the requirements to activate the action.
It doesn't work because you can't put both hands on your weapon.
It doesn't work because you can't put both hands on your weapon.
It doesn't actually say that: "You can wield weapons you are Juggling (but not shields or other items) as long as they can be wielded in one hand" doesn't mean 'you can't wield it in 2 hands': IE, it prohibits 2 handed weapons, not wielding in 2 hands.
The issue with it, IMO, would be "The item must be of light or negligible Bulk." You'd have to say that the bulk of your arm + weapon would be Light or less bulk which seems unlikely.