Saponification is a chemical reaction between triglyceride and a strong base. Triglycerides are formed from glycerol and three fatty acids. Ester bonds are formed in triglycerides because of the connection between glycerol hydroxyl groups and fatty acids carboxyl groups.
In saponification reactions and in the presence of heat, the strong base cuts off the ester bonds in triglycerides, replacing the fatty acid chain with a hydroxyl chain.
If during a saponification reaction a strong acid is introduced, such as hydrochloric acid, it stops, because hyroxyl groups are reduced and the solution becomes neutral, or even acidic.
Hence, even though a strong acid does not directly react with ethyl acetate, it slows down the saponification reaction and can even stop it.