Speaking from first hand experience, you'd be surprised at how many more lines of code are required to fix that problem than your estimate of 1 line
Bombers are the only unit in Civ 6, that can actuall stack up, to 4, or 6UPT max.
It seems logical to an extent the the most powerful army weapon is deliberately removed from the code.
Bombers are effectively the only (limited) stack of doom feature that went though the ages.
What are the odds that there are no lines of code whatsoever regarding 'Air superiority' other than some dummy Agenda lines?
Civ V was quite different in using the stacks of Bombers. AI would build Sam units and surround cities with them asap they got the technology.
CIv 3, on the other hand, you could stack a flack unit, or SAM, into an army, with one infantry on top, and use inside your capital city to defend it against bombing raids.
The Army would take damage, and prevent the city structures to be damaged or destroyed. The AI without Army would consequently get completely crippled if an enemy
decided to bomb their capital. Bombing raids could reduce pop size to 1, and destroy all of its buildings. Only a composite army could save your cities.
RYYE AI used to stack also siege units, and move them along the files, and use them in field battles and in sieges. Again, armies even in ancient eras, were the only mean to survive
if such threat was incoming. Lines of code back then where much simpler also... maybe not 1 line of code though

(I'm leaving POSITIONAL, ATTACK and STRATEGIC tacticals lines empty, for obvious MAP related reasons in this example).
Computer player A1, beginning of turn:
Evaluate if A1 is at WAR/PEACE
Evaluate BEST current defensive tactics in WAR POOL and compare the odds with long term CIV AGENDA POOL.
IF odds are greater than >1 than OVERRIDE CIV AGENDA POOL
WAR POOL includes:
Is A1 the aggressor or the aggressed?
IF A1=aggressor then use BLITZ tactic
IF A1=aggressed then use GUERRILLA or TANK
Is A1 armies at great disadvantage or at great advantage?
IF disadvantage use TANK. IF NOT, use GUERRILLA.
Evaluate, available LEADER YES/NO
IF YES then BUILD ARMY-n
IF BLITZ then evaluate best ARMY-n possible composition for FASTER ARMY COMPOSITION and deploy for ATTACK.
IF GUERRILLA then evaluate best ARMY-n possible composition for ENEMY MAX THREAT and deploy for STRATEGIC defence.
IF TANK then then evaluate best ARMY-n possible composition for ENEMY MAX THREAT and deploy for POSITIONAL defence.
IF NO then prioritize ELITE units to move towards weaker enemy target (in order to maximize chances to create a LEADER)
$ All tactics includes armies and divisions.
$ tactical divisions are deployed by their composition to either one of possible tactics pools.
$ armies compositions should be split using units cost/power ratio to determine units allowance per division composition.
$ ARMY-n can serve more than one tactical division role, and be used accordingly
$ (e.g. has an Anti AIR U value > 0 then can be used for POSITIONAL defence, but if it has also an attack value > 1.1X enemy max defence UU then also ATTACK).
$ (e.g. Persian Immortal inherent values is 40 to build, 2 to mantain, and has 6/2/0 in offence/defence/ranged. formula in question should also consider other variables such as capacity for A1 to produce per turn.)
$ (IF a city can produce 120 per turn, does that means that 80 are wasted per turn, or the city can produce 3 UU per turn??
$ Optimize Military production efforts should be a focus for any formulas inquiring armies and divisions production and composition.)
TANK tactics includes:
armies compositions units class priorities:
ARMY-n > Spearman > Anti AIR > Bombard > Guerrilla, Paras > Warrior, Marine > Ranged > Cavalry
TANK tactics also includes minumum divisions requirements for basic defence for the empire at all moments. Be country at WAR/PEACE.
divisions numbers should be calculated equal to numbers of cities with pop greater than > 3 pop
divisions should be deployed to each city > 3 pop. otherwise cities with lower > 3 pop should follow basic GROWING CITY orders (eg 3 ranged > 3 spearman > 3 warriors)
GUERRILLA tactics includes:
armies compositions units class priorities:
ARMY-n > Guerrilla, Paras > Warrior, Marine > Spearman > Bombard > Ranged > Cavalry > Anti AIR
BLITZ tactics includes:
armies compositions units class priorities:
ARMY-n > Cavalry > Guerrilla, Paras > Bombard > Ranged > Warrior, Marine > Spearman > Anti AIR
CLASS units i.e.
Bombard class includes: Catapults, Trebuchets, cannons, artillery, WWI Bombers, Bombers, Strategic Bombers, Quadriremes, Dromones, etc...