While Einstein was extremely good at math, he didn't invent the math that he used. For example tensor calculus was invented by Tullio Levi-Civita. Einstein learned it from Levi-Civita's textbook, and then Einstein and Levi-Civita had a lengthy correspondence in which a number of Einstein's misconceptions were cleared up.

But including Feynman in that list is an egregious joke. Richard Feynman was one of the top mathematical talents to grace physics. He was a lightning fast calculator. I know of two math competitions that he was in (one from NYU, the other the Putnam). He won both by wide margins. He was the only student ever to get a perfect score on both the math and physics sections of the Princeton graduate entrance exams. He invented a whole series of mathematical techniques, Feynman diagrams being only the most famous.

Einstein was merely extremely good at math. Feynman was phenomenal. Neither is a good example of physicists not needing to be good at math.