If his history is so good it’d be better to briefly touch on it early on so it would be a positive rather than leaving the opportunity for people to wonder why it wasn’t disclosed. There’s no downside to being scrupulous about this and it can make a story more compelling when someone explains how their position evolved.
Because it's not important any more than knowing whether you or anyone else is member give that to the extent you can call him a lobbyist he is a lobbyist for his own mission.
He isn't working on the behalf of some industry he is working for a case.
He cowrote a paper with Brand from the long now foundation about nuclear.
Being a lobbyist isn't just one thing even though it always get's used like that and it doesn't mean you are working for some industry.
It’s always important to know about conflicts of interest. If his intentions are good, he should be especially keen on avoiding any risk of being seen as deceptive because that would hurt his stated goal and there’s no downside.
What about you start by being concrete and put forward any evidence of issues with his so called lobbyism. This attempt at weakening his argument by claiming he is somehow in bed with the wrong people instead of actually proving he somehow have husky alterier motives is absurd. I dont see people complain about all the scaremongering by environmental organizations.
And if you want to claim that you also have to claim that on the other side, i.e. the environmentalists.
But with Shellenberger it's an especially absurd argument which you would know if you actually knew who he is and what he is fighting for and how.