If someone admits in chat that he caps sh gy because he needs to farm honor on his alliance toon, then shouldn't this be considered wintrading? I don't have to point out the strategical disadvantage of this (and iceblood for alliance) action, do I?
/discuss
Someone from the staff should probably answer on this as they know the policy on their server better than anyone.
AFAIK the issue here lies in the fact that a person is double-accing a BG on different sides in order to provide an advantage/disadvantage for either side. Not to mention this is done solely to grief the opposing side for one's own interests. Hence the statement of wintrading is not the most accurate way of putting this.
An action like this breaks so many rules I believe a ban is more than warranted if proof is presented of this.