Well, I know you know better, but, to all who may believe as such, Yata Mirror cannot oppose it, because kamui technically wouldn't be attacking it, it would be moving one section of the mirror somewhere else, not bashing it head on.
attack
əˈtak/Submit
verb
1.
take aggressive military action against (a place or enemy forces) with weapons or armed force.
"in February the Germans attacked Verdun"
synonyms: begin an assault, charge, pounce, strike, begin hostilities, ambush; More
antonyms: defend
act against (someone or something) aggressively in an attempt to injure or kill.
"a doctor was attacked by two youths"
synonyms: assault, beat, beat up, batter, thrash, pound, pummel, assail, set upon, fall upon, set about, strike at, let fly at, tear into, lash out at; More
(of a disease, chemical, or insect) act harmfully on.
"HIV is thought to attack certain cells in the brain"
synonyms: affect, have an effect on, strike, strike at, take hold of, infect; More
2.
criticize or oppose fiercely and publicly.
"he attacked the government's defence policy"
synonyms: criticize, censure, condemn, castigate, chastise, lambaste, pillory, savage, find fault with, fulminate against, abuse; More
antonyms: praise
3.
begin to deal with (a problem or task) in a determined and vigorous way.
"a plan of action to attack unemployment"
synonyms: attend to, address, see to, deal with, grapple with, confront, direct one's attention to, focus on, concentrate on, apply oneself to; More
4.
(in sport) make a forceful attempt to score a goal or point or otherwise gain an advantage against an opposing team or player.
"Crystal Palace attacked swiftly down the left"
CHESS
move into or be in a position to capture (an opponent's piece or pawn).
"the white queen attacks the black rook"
noun
noun: attack; plural noun: attacks
1.
an aggressive and violent act against a person or place.
"he was killed in an attack on a checkpoint"
synonyms: assault, onslaught, offensive, strike, blitz, raid, sortie, sally, storming, charge, rush, drive, push, thrust, invasion, incursion, inroad; More
destructive action by a disease, chemical, or insect.
"the tissue is open to attack by fungus"
a determined attempt to tackle a problem or task.
"an attack on inflation"
forceful and decisive style in performing music or another art.
"the sheer attack of Hendrix's playing"
2.
an instance of fierce public criticism or opposition.
"he launched a stinging attack on the Prime Minister"
synonyms: criticism, censure, rebuke, admonition, admonishment, reprimand, reproval; More
Note the noun part under section 1. You can call it whatever you want but it is an attack. And if it is an attack, Yata can counter it. We both aren't right or wrong because there's no evidence of it, we can only rely on our logic.
Kamui is a transportation technique and not an attack so it cannot u.u
Kamui forcefully distorts the space, so by logical definition of an attack, it's an attack.