That's what you have to learn in that question ::

CREATE TABLE dbo.A (PK int not null primary key clustered)

GO

CREATE TRIGGER dbo.trDemoA_IUD ON dbo.A

FOR INSERT, UPDATE, DELETE

AS

SET NOCOUNT ON

ROLLBACK TRANSACTION

RAISERROR ('Cannot allow any DML operation on table A', 13, 1)

SET NOCOUNT OFF

GO

INSERT INTO A (PK) VALUES (4)

GO

DROP TABLE dbo.A

GO

This transaction will rollback even if I didn't create the tran myself.