Sated Devourer

As someone who uses thornmail to counteract some of these life steal people like Aatrox, and trundle...... i feel that the new sated devourer nullifies it completely by letting them have a free attack with no remorse, as in even though its a second attack and applies on hit effects, it doesnt activate thornmail a second time.... if it did this, then someone wouldnt be able to be gaining health when attacking someone with a thornmail by just having a Blade of the Ruined King and a Sated Devourer.