Try to push this case with support of your local mods Xandry and Xal0lex. They can vouch for him.
Xandry already merited (which means "support" i think) this topic. Also, 3 DT1 members
TheFuzzStone,
Alex_Sr,
taikuri13 which all trusted members in russian and english boards, supports unban. Does it not enough?
Are these 3 DT members are in Theymos trust list? I think theymos is trusting the moderators more than anyone else in this forum.
Xandry meriting it and not writing anything does not clear the picture at all. I am not sure whether Xandry merited it for your effort or whether Xandry agree. (In real sense, Merit does not means I agree, Instead it means I appreciate your logic or reasoning.)
PM Xandry, a personal vouch by him to theymos/Hilariousandco will definitely make things smooth.