In reply to J1234:
It's a very interesting philosophical point. In practice, it's probably a more pertinent issue in the US than the UK where there is a long established tradition of (taxpayer assisted) philanthropy by the rich and mega-rich.
Anyway, I'm slightly surprised that there does not seem to be any maximum limit on the gift aid claimable as long as it is less than whatever UK income tax you would otherwise pay.
However, back to the main issue - is the RSPB more interested in conserving the environment or running a tourism business?
From it's statement on FB you could be forgiven for thinking it's a bit too preoccupied with the latter. There was much talk about "increasing visitor numbers" and "high quality facilities" and not much detail relating to its conservation efforts. There isn't even a token effort to greenwash the proposals by spinning them as encouraging car sharing or by offering free parking for electric vehicles.
Overall, probably not going to be a good PR move for the RSPB.