Retirement plan obligations are liabilities because they are liabilities in the accounting sense of a liability.
It is money for which the employer is legally obligated to pay or encumber on the behalf of an employee and is not money that the employer has freedom to use in any fashion it wishes, therefore the agreement to make certain benefits available under the plan are a liability to the company, as would be the case with any other legally agreed upon obligation.
It is money for which the employer is legally obligated to pay or encumber on the behalf of an employee and is not money that the employer has freedom to use in any fashion it wishes, therefore the agreement to make certain benefits available under the plan are a liability to the company, as would be the case with any other legally agreed upon obligation.