However, it's a simply thing to mod it into a choice if someone wants to do so instead.
Very simple

Here is a basic event you can use if you aren't into writing your own events.
Just add this event to
Victoria\db\tech\army_inventions.txt.
Then add this line:
invention = 199
to the trigger section of events 100 (Jominian Attitude) and 101 (Clausewitzian Theory).
################################################
# Military Theory
################################################
event = {
id = 199
random = no
invention = yes
trigger = {
technology = 1001
NOT = {
invention = 100
invention = 101
}
}
name = "Military Theory"
desc = "Choose which doctrine will be followed in organizing our military. The Jominian attitude emphasizes morale and leadership, while Clausewitzian theory focuses on organization and technological innovation."
style = 0
picture = army_doctrine
date = { day = 1 month = january year = 1836 }
offset = 60 # Check for trigger conditions every 60 days
deathdate = { day = 30 month = december year = 1846 }
action_a = {
name = "Jomini"
ai_chance = 50
command = { type = trigger which = 100 }
}
action_b = {
name = "Clausewitz"
ai_chance = 50
command = { type = trigger which = 101 }
}
}