Lawyers have a duty to provide the best case for the client they represent. They have an ethical duty not to lie or actively hide the truth, but that's where it ends. They are not supposed to inject personal feelings or morals into the case. It's a different situation for the District Attorney or other official who decides what to prosecute someone for, but once it's assigned to an attorney, they have one goal - to best present one side of the case within the constraints of the law.
The brake shoe was really bad taste, but winning is everything for an attorney - it's their job.