Stop making excuses, and stop being your Dad's codependent enabler. If you take off the plates, and your Dad drives and kills someone when his brakes fail, it's his fault. If you let this slide, it will be your fault.
(Yes, calling you a codependent enabler is a bit harsh, but I think it's valid, and I think you can take it.)
You can be dishonest with your Dad and sneak his car out to a shop for repair, if that is easier. Or you can confront the problem openly. Scrape off the inspection sticker and make him get it reinspected. Report him to the police for faulty equipment and bad eyesight. Take the car away and hide it and let him report you for theft. Better that he hate you than that he kill someone.
And God forbid he gets in an accident and seriously injures or kills someone, and the police find duct tape on a leaking brake line. That will prove he knew he was driving with dangerous equipment. That's criminal negligence and makes him liable for manslaughter charges, not to mention a lawsuit that will drain whatever remaining assets he might have.