It is speculated that much of the lobbying that occurs is by the influential people in an unregistered capacity and it's known as "shadow lobbying".

"1. I will not, within 5 years after the termination of my employment as an appointee in any executive agency in which I am appointed to serve, engage in lobbying activities with respect to that agency."

... and there is the "out". Just engage in lobbying activities with respect to another agency, where you now have a lot of contacts. Or consult with an agency that does engage in lobbying activities with respect to that agency.

You get the idea.

I am happy that the "Revolving Door", made famous by Larry Lessig (whose writing and classes, if you are lucky, can't be recommended enough) is getting more than lip service from some branch of government. However, this is just barely more than lip service.