I think this is false advertising. You are really NOT stopping an update or delete statement without a "WHERE" clause from running, you are just comparing the number of rows affected to the number of rows in the table, or maybe not, as others have been added concerns about index's adding to the rowcount.

What if someone actually does need to update all the rows in the table. What if the update statement does have a "WHERE" clause and all of the table rows meet the criteria of the where clause.

I can see this creating problems, especially down the road when someone else is maintaing the database. I would not recommend using this code, sorry.