While I agree with the sentiment, keep in mind it's a little more complicated than that. People who work on some category of regulations can only find relevant work in the government or in that sector of industry. Making it impossible to move from the government to an industry job effectively traps people for life in their one job unless they change careers.

As a concrete example, my fiance is a lawyer working in environmental policy. She's worked for the EPA and for various environmental justice groups because she went with whatever jobs were available in her field, and that wouldn't be possible with your proposed change.