Kaboom + Faerie Fire + Acid Bomb?

While replying to a comment on my previous post, I decided to look up how much damage Sapper's Kaboom! does. My idea was that a Shredder could, on a map such as Twisted Meadows, cut along the back line of trees towards the back of an enemy base, then deploy some Sappers through the new back door. Maybe target these:

Entangled Gold Mine: 800.2
Haunted Gold Mine: 800.5
Peasant: 220.0
Peon: 250.0
Wisp: 120.0
Acolyte: 220.0
Ghoul: 340.0:6
[ Unit/Structure: HP.MinArmor:MaxArmor ]

Kaboom!
Deals 750 damage to buildings, 250 damage to all units, 185 damage to Heroes. These values are reduced by armor values such as '5 armor', but do not interact with armor types such as Medium armor. Effective against buildings and trees. Using this ability destroys the Goblin Sappers.
Full damage radius: 10. Half Damage Radius: 25.

Does this mean that a unit with negative armor takes more damage from Kaboom?!