I believe the brake problem was caused by a faulty seal, which may have been supplied to the part manufacturer by another 3rd party. This is a long chain of responsibility for quality control with MMC at the end of it. For Morgan to have picked up the fault during assembly, they would have had to disassemble and check every unit and even then a faulty seal may be very hard to detect.
Regardless of the law, I personally feel that Morgan have been unfairly criticised over the recall and other company's quality control failed before Morgan's and left MMC in an impossible position.