Most sweepers usualy don't have to palm mute to eliminate the ringing of notes , so it's more of a question of tone , muted tone or normal tone . For me , it depends on the mood of the song .

Anyways , Malmsteen palm usualy mutes when he sweeps , and the tone doesn't seem to be much palm muted since he use very light palm muting for the sweeps , the distortion and the background music take care of the rest.