Up to a certain point, yes - if you never leave the U.S. and don't anticipate that the U.S. government will at some point extradite you to the UK. And if you travel to other countries, one of those could decide to extradite you to the UK. That is less likely with a lawsuit from Zimbabwe than a lawsuit from the UK. In other words, it depends on how much international influence the country in question has.

Only if you're okay with never visiting or transiting through the UK, or any other country that would be willing to extradite you there, for the rest of your life.