Obviously people actually setting fire to his gates are plain lunatics: www.bbc.co.uk/news/uk-england-hampshire-58861252. The article talks about all these other online threats, dead animals and other mischief however, which implies a fair number of individuals who expend time and energy going after him. He's just an environmentalist campaigner who wants a bit more wild space, a few beavers introduced, fewer birds shot... he isn't a man of great power. So what do these people fear so much?