Yeah a bit loose isn't it. When the reports of the 16 and 60s year olds being arrested came out so quickly, I thought they probably had something half meaningful there to act so quickly. Rather than, the closest known farmer with a bit of a grudge against something not even that related.
According to other reports, his dispute over land is well known, and he supposedly threatened to cut the tree down previously. But his dispute is also with the Jesuits, rather than the National Trust. So, unless there is a link I don't know about seems a very ineffective way to fight or avenge his cause.
Stating the obvious, we don't actually know anything, there could be a lot more, or less to it in reality that the police have. It is just a comment on the articles, and what is out in the media.