So only people who are unemployed can talk to politicians. Or do you want to make it illegal to give someone that particular job title? Do you see what I'm getting at?
I think you're being particularly obtuse. There is no reason that you can't give anyone any job title you like so long as they are not a government official. What laws should do is make it illegal for corporations and foreign governments and organizations receiving donations from either to contribute money to election funds; run political advertisements; or provide gifts, food, travel/travel expenses, entertainment, lodging, etc. to anyone in political office (elected or appointed) or to their relatives.
Sure you may not be able to ban individuals from going to visit congress critters and appointed officials, but you can sure as hell make them less likely to be received since they won't be bearing gifts or swaying an election in exchange for wink wink whatever. Sadly because of absurd Supreme Court rulings, such a law would most likely require a constitutional amendment, one that specifically states corporations are not individuals with the rights of individuals. I actually think this is doable as a grassroots reform movement and people could really get behind an independent party or group of politicians honestly trying to reform the laws and clean up the system. It certainly has popular support.