No it does not negate aim assist. Reduction of aim acceleration can cause the feel of a lack of aim assist at med-long distances with long range weapons.
As I previously mentioned when talking about aim acceleration as a choice, this setting could have adverse affects. While your close range engagements and even building may feel better, small movements when trying to have a precise shot at med-long range may feel off.
This is just the way aim acceleration works. I will even say I was playing on 0 aim accel for a while, but ended up turning back all the way to 100 due to my engagements with my AR not feeling the best.