Personally, I think toughness would be hitting back when a hyper-partisan unethical prosecutor files a frivolous charge against one of your top campaign people in a blatant act of political spite. File away Trump.
We had 8 years of Bush never even speaking out, let alone hitting back. It would be nice to have someone who fights for his side.
All Trump could do is make a complaint - he cannot file charges. The police or the prosecutor would have to determine if there was evidence of a crime and then decide whether or not to file charges.
This just shows why Trump is such a bad candidate and would be a horrible president. All he or Lewandowski had to do was say, "Sorry, we didn't realize he grabbed you so hard." Instead, they tried to slime and attack the reporter, and they keep doubling down even after proof that they lied about the incident. Instead of focusing on his campaign, he is wasting time tweeting and making silly statements ("her pen could have been a bomb!") over an incident that should have been resolved the day after it happened.