Maybe I'm missing something, but if I had made such a comment on a public platform and
any of my previous employers learned of it, I could 100% expect to be terminated if it came to light. Whether his final philosophical view on the matter is morally correct or not is not the focus here. I can completely understand why a foundation would not want a man who apparently had to be talked into understanding why sex with a child is wrong to be its very visible leader.
You're talking about a role that has to inspire by example, someone responsible for advocating for your institution publicly, recruiting supporters, and so on. No one who has a history of making incredibly suspect comments about children and sex should expect to stay in such a role.
Incidents like this are NOT about setting up an ethics court and decide the morality or immorality of the person's views. They're about an organization waking up one morning and saying, You know what, we really would rather not have someone with a history of bizarre pro-pedophilic comments as our leader. For god's sake, how would you feel if your CEO had a personal web page with a history of arguing for lower age of consent laws? At a certain point people just don't want to come 'work for' such a person.
And really, who among us would be surprised to wake up and find "RMS indicted on child porn charges" on the front page news? People with normal views on child sex topics tend not to be the ones out there talking about 'ephebophilia' and "now I'm no psychiatrist, but here's my argument for why children actually CAN consent to sex with adults." I'm not saying I'm convinced he's a pedophile, or even that I believe him to maybe be one. It's just not a revelation that would shock me.