It can hurt being accused of something you did not do. Your name, reputation and what is written about you and known is very important. If he hadn't gone the extra mile to clear his name considering that he was fairly confident in his ability, history will remember him as the biggest cheat of that time even though it wasn't the truth. Some things are worth more than money, and reputation is one of such things which you must take seriously, if it is within your financial ability to prosecute whosoever tries to ruin your reputation, you should do it without minding the cost.