1. we don't know their age, we only know they were virgins
2. they could be adult virgins
3. they deliberately made him drunk so he won't know anything and forced him to have sex with them not remembering it
not sure how is this CSAM, just because it's incest, doesn't mean it's CSAM, and by your logic they were his "children", then everyone is someone's child and literally all porn is CSAM then
The situation was such that they lived far off because their city was destroyed. There would've been no more offspring. Oddly enough, Lot is a man and his daughters slept with their father.
Anyway, the sex was incestuous and therefore your conclusion is invalid because it disregards that fact. Of course when adults of different families have sex it's not child abuse, that goes without saying.
But you do have a good point that the age of the 2 daughters wasn't mentioned.
Whatever their age was, they were betrothed to be married to men who didn't evacuate when warned:
14 So Lot went out and spoke to his sons-in-law, who were pledged to marry his daughters. He said, “Hurry and get out of this place, because the Lord is about to destroy the city!” But his sons-in-law thought he was joking.
2. they could be adult virgins
3. they deliberately made him drunk so he won't know anything and forced him to have sex with them not remembering it
not sure how is this CSAM, just because it's incest, doesn't mean it's CSAM, and by your logic they were his "children", then everyone is someone's child and literally all porn is CSAM then