Answer: No, it is not the bisector of angle ACB
Angle ABC has the vertex at point B. The middle point determines the vertex. This is why angle ABC is the exact same as angle CBA. Each time, B is in the middle.
However, angle ACB has point C in the middle so we're talking about a completely different angle. This is not a bisector because the line doesn't even go through point C at all. The line would need to curve, but bisectors must be straight lines.