Inclining of columns is not accepted in construction. The columns must be truly vertical. In some cases, a deviation of 10 to 15mm or 2 to 3 % is permissible.
Yes, if the columns are not verticle the load transfer which happens via column is not 100%. This affects the durability and life of the building. Due to this, there might be a risk of safety during calamities.
The justification is given by the supervisor is not correct. To rectify the mistakes done during the casting of columns, the columns are plastered to make them look truly vertical.