If it is illegal for serving SES employees to receive royalties on patents (and keep the money) then this is a problem.
If not, it isn’t.
Does anybody know? If 1675 scientists at NIH received $200K each in royalties in their careers, and if it is legal, it doesn’t seem like a big deal.
I don't know the policy for Fed scientists, but as a worker bee at a state research university it was somewhat common for professors to have side gigs. They aren't suppose to mix grant research with their private activities and have to to fill out yearly conflict of interest forms. The rules were relaxed during years of small pay raises. I suspect a similar approach was taken at the federal level.