from my knowledge a person can only get sexually intemate with such a young mate if he/she is a minor him/herself.
I don't know which is worse, your lack of knowledge or lack of common sense.
First, no it's
not legal for a minor to engage with a minor in most Western countries, since it's considered statutory rape. Whether this is fully enforced or not is another issue, since you rightfully pointed out that Thailand for instance does not fully enforce its age of consent laws as well.
Now if it were legal for a minor to engage with a minor, then our argument still stands, because the developer should allow the game to be modded for under-18 users, who would then not be breaking the law by playing with underage characters. While if they played with legal-age characters the characters would be statutory raping them
(wtf this is getting really weird).
And lest we forget, I'm reminding you again that even real child porn
isn't criminalized in many countries, and among those criminalizing it the
vast majority doesn't give a shit about cartoon depictions, much less fictional "numerical" depictions. That enforces our argument that hard-coding an age limit in the .cpp files, not just the easily modifiable .girls files, is an overstretch.
For the love of Feminism, do a 5 minute research before spreading FUD.