When Yasuo Unforgiven is moved into a showdown using Tideturner during the opponent's attack, does Yasuo trigger his attack damage ability?

Ruling: Yasuo Unforgiven does not deal his attack damage when moved into a showdown via Tideturner during the opponent's attack, because he is defending, not attacking.

Nuances:

• The showdown belongs to the original attacker, so units moved in by the defender are considered defending units
• Only attacking units trigger attack-based abilities during a showdown