Weapons or Armour 1 first?

After watching the Saunamen vs Snails game for NSL, I noticed they rush Weapons 1 first.

Here is some math of why I think this happened:

Killing skulk under <2 seconds
70 + 10 armour + 1.4 hp regen = 91.4hp
Weapons 0 = 10 bullets = 100 damage
Weapons 1 = 9 bullets = 99 damage


70 + 30 armour +1 hp regen = 131.4 hp
Weapons 0 = 14 bullets = 140 damage
Weapons 1 = 12 bullets = 132dmg


Killing skulk under <4 seconds
70 + 10 armour + 2.8 hp regen = 92.8hp
Weapons 0 = 10 bullets = 100 damage
Weapons 1 = 9 bullets = 99 damage


70 + 30 armour +2.8 hp regen = 132.8 hp
Weapons 0 = 14 bullets = 140 damage
Weapons 1 = 13 bullets = 143dmg


If you can kill the skulk in under 2 seconds with weapons 1 LMG, instead of carapace providing an effective HP gain of 40%, it will gain 20%.


If you can kill the skulk in between 2-4 seconds with weapons 1 LMG, the effectiveness of carapace will be 30% and not 20%.

Shotgun on Fully Matured RT
Note: Res towers do not have passive regeneration


Shotgun shot lvl 0 weapon = 160 damage
Shotgun level 1 weapon = 176 damage


HP = 2940HP


Weapons 0 = 19 shots = 3040dmg
Weapons 1 = 17 shots = 2992dmg


LMG on Fully Matured RT
Level 0 = 294 bullets or 6 LMG reloads
Level 1 = 268 bullets or 6 LMG reloads


Summary
Weapons 1 has nearly zero benefit killing a fully matured res tower.
Weapons 1 reduces effective HP of carapace skulk by 20%, instead of 10% if killed in under 2 seconds.

My opinion is armor 1 is still stronger, but after seeing the top teams go weapons 1 i'm questioning myself. Any other reasons you can think of?