Since Insulin is unable to act on cells due to insulin resistance, then shouldn't ketoacidosis also occur in Type 2 ?
Actually, ketoacidosis could occur also in Type 2 Diabetes. It's not common, but it's a possibility and should not be not omitted.
In Type 2 Diabetes the insulin secretion is available but insufficient to meet the glucose needs. However, generally, can prevent sustained hyperglycemic states that could lead to ketoacidosis.
When DKA occurs in patients with type 2 diabetes, the presumed mechanism of ketoacidosis is the combination of relative insulin deficiency and increased secretion of glucagon (as well as other counteregulatory hormones such as cortisol, catecholamines, and growth hormone) in response to stress from 1) overwhelming infection, 2) infarction of tissue, or 3) other severe illness. The elevated catecholamines further suppress insulin secretion to perpetuate a downward spiral. The increased glucagons-to-insulin ratio causes a mismatch that promotes unregulated lipolysis and proteolysis with subsequent uninterrupted formation of ketoacids.