(a) That is a beautifully written line.
(ii) I don’t really agree with you. I think it’s just a bit more banal than that. Corporate culture invites corporate responsibility. Corporations are scrutinised, and just because this is a site of historic interest, and ostensibly a charitably run one, doesn’t mean they don’t have to account for eg public liability insurance, workers rights and the nightmare balancing act of having paid and unpaid workers doing the same job - that last alone probably blows the idea of retaining the former volunteers as volunteers out of the water.