Must say I've never bought into the paganisation of the Green Man favoured by fundies. The medieval minster builders, people who weren't averse to the odd Doom painting, never AFAIK elided foliate heads with Old Nick as visual simulacra. Iconoclasts, men you'd assume would have a grudge against this particular idolatry, don't appear to have singled out leaf faces for their ire and big hammers.

The Green Man in pub signage sees him as Robin Hood, Jack in the Green and the Jolly Green Giant of tinned food fame which is also a bit of a presumption IMO. My suspicion is the foliate head in churches had some significance which was fully compatible with a Christian reading to their builders that has been lost. TGM could be a personification of summer (like moons and suns have faces) without implying an extra deity, or the abundant wood the beams are made from, or a visual signifier for all acts of human creation - but we're in the world of guesswork.
Conspiracies are one of the better uses for Occam's razor. There's no need for goblins.