It's not a crime for any ex politician to joining a lobbying group, in fact many of them do just that after they're defeated or retire from politics.
I don't see how that is anything to be proud of. It's often just plain corruption. angelo, I will explain to you how it works, and I will use as an example a kind of business that I'm sure that you think ought not to exist, so you might find this example easier to understand.
Imagine a maker of photovoltaic-cell solar panels. I will call it SunVoltage. I run for public office, with SunVoltage financing my campaigning through a PAC to get around direct-contribution limits. Once in office, I insert big tax breaks for SunVoltage into tax and appropriations bills. Out of office, SunVoltage quickly congratulates me for my service to the company and hires me as a lobbyist. I then use my public-office connections in my efforts to lobby for more special treatment for SunVoltage.
angelo, wouldn't you hate it if fossil fuels lost as a result of crony-capitalist corruption?