The Shooting roll may face a cover penalty (if trying to fire past the adjacent foe), and I would also say that someone using the weapon to make a ranged attack is not simultaneously using it as a Improvised Weapon (meaning they are effectively an Unarmed Defender and +2 to be hit by an adjacent foe or foes with a weapon).
but this later thread says the exact opposite
It could be played that way if the group prefered it (since the rule affects all characters equally), but "officially," if a character had a viable improvised weapon in their hand, they would not be an Unarmed Defender even if they used that item for something else as an action. It's simpler and easier, plus it's not like a character is considered unarmed when they choose to attack with a melee weapon, so why when they choose to attack with an Improvised one (even if that attack is shooting).
Which ruling is correct? (or are they talking about different things and I have my wires crossed?)
EDIT: On re-reading the first thread I see it mentions shooting at someone other than the person attacking you in melee, does the target of your (shooting) attack make a difference to whether or not you are considered to have an improvised weapon to defend with?