What is the ruling, according to the Maliki school, on one who does not perform or pronounce "As-salamu alaykum" during the second salutation in prayer, on the left side?

According to the Maliki school, only one salutation is obligatory. It is recommended for the congregant to offer a salutation, gesturing towards the Imam, in response to him. He should also offer a silent salutation to his left if there is another congregant. The salutation should be with the heart, not with the head.