Here is one problem with your view as per my edit. I do not think speculation can be used to debunk an assertion. The assertion being the vote passed so thus the group was fine with it.
Using my role to my advantage is still speculation on my part since I have no evidence to prove other wise. That is just my theory why it passes.
As for having a friend to stack the vote we are still part of the group and since the person being voted does not get a say in FFXIV the vote remains with the remaining 3 so if it passes even though I brought a friend it is still the will of the group.
The argument still stands that if the vote passes it is the will of the group. The vote passing is the only binary objective action we can go by. Did 2 out of the 3 remaining members vote in favor or against. That answer is an objectionable truth in this matter. Everything like me saying using a role may sway the vote is spectaculation. It may sway someone's vote and it may not. Me bringing a friend is moot since they are still part of the group.
Nothing I have said goes against the notion if a vote passes it was the desire of the group.
In the end the mere possibility without being able to prove the counter claim is not grounds to dismiss the notion that the outcome of the vote is not the desire of the group. Either it be positive or negative.
In the end the burden would be on you to prove my actions lead to peer pressure. Which cannot be done unless you are able to ask the party members of the group if they felt pressured or not. Do not get me wrong I do not dimiss the possibility and it is my theory why they pass but that is still just my theory and own speculation why a large number of my votes pass.
This is probably also why SE GM's might also be annoyed with such cases they legitimately cannot do much dispute maybe having a proper gut reaction. Granted I would be in trouble if GM's ruled off emotion but thankfully they do not.
Granted you could say me bringing a friend is manipulation but then that creates the questions should people that queue together not be able to vote cause it is unfair or should those that group togethers vote be counted as one.
Also the thing with just because something can be done does not mean it should be done. Is also just your belief, which I respect but I do not share. If SE wants to do something about this then they need to start enforcing their ToS.