Loads of people can explain why. You just refuse to listen and want to keep your car over anything else.
Turning off the airbag is disabling a safety feature that will impact on other parts of the scenario in a crash. You’ve also failed to read the manual properly, any old car seat won’t automatically disable your airbag but you assumed it would. That’s so fucking dangerous.
The proximity to the windscreen.
The fact that you’re more likely to be crashing from the front than not.
The well known fact that the rear middle seat is safest for everyone, especially children and infants who suffer the impact of a crash worse than adults in certain situations.
You don’t want any actual scientific information, you keep saying you do but it’s clear that you just want to keep the car you’ve got. Otherwise you’d return to the dealer, explain your situation and, even if it costs you a small amount, you’d put your child’s safety first.
Here’s some reading anyway,
In regards to child safety, (Braver, Whitfield, & Ferguson, 1998) found that among children under 13 years of age, fatality risk was 38% lower for properly restrained rear seated children compared with those positioned in the front seat Braver et al. (1998). A more recent study by Winston et al. found children were 40% safer in the back seat than in the front when involved in a crash and that the risk of injury dropped to less than 2% when these rear seated children were harnessed in age appropriate restraint systems (Durbin, Chen, Smith, Elliott, & Winston, 2005).