That's an easy problem to solve. The people with the trading algorithms can just learn to program. No worries about programmers stealing trading secrets that way.
HFT financial engineers can not necessarily learn software engineering in their operating time-frames. There is no "High Frequency Learning"; by the time they learn to configure a development environment they could have lost the edge.
It's a lot easier for a good programmer to learn how to trade than for a good trader to learn how to be a programmer. Though most programmers make terrible traders and most traders make terrible programmers. A lot of depends on the company you are at, the more foresighted ones, were grooming guys for this role 5-10 years ago. And more importantly establishing a tradition of `trade developers.` Typically though the traders that become good enough programmers took an engineering discipline in college. Also, some of them are just so smart / driven that coding something good enough to make money is something they trudge through, but their code usually the ugliest thing you'd ever see this side of php.