I think there's a lot of resemblance with the oak trees doing all of that brainwashing thing to Lucas's resonating power evoking his own feelings upon the people for them to cause mass murder. The author is definitely setting up a dilemma or thoughtful reminder that Lucas might be no different than the ones he's fighting against(which is probably obvious from the previous chapters). Definitely, there will not be a grand ending for this story. A grim one for Lucas.
You say this as if it's speculation, but aren't they pretty much confirmed to be the same thing? All the Ramus are tree-hybrids or something. We figured that out back during the oakist village arc, where they strapped Lucas to the chair since they wanted to mPreg him, a Ramus (tree power wielder), with a tree seed or whatever.
In terms of being no different from the enemy, that was always the theme. Every since we knew other nations had Ramus (that were also coerced into service), their own tower/tree/spire thing, and the time-travel leaders.