One of the scientist's jobs is to report the results of his experiments to all the other scientists in the world.
There isn't a single real science shop anywhere in the world that uses the US customary system of units. Not one.
Even in the measly three countries that use it for measuring carpet, pumping gas, and weighing fish ... Myanmar, Liberia, an the USA ... the scientists do their work in the SI/MKS/metric system.