Exclude User from Activity Stream in BuddyPress?

I’d like to exclude a specific user account from showing up in the activity stream.
I found this code that’s supposed to exclude the Admin. Any clue how to exclude a specific user? (this code goes in bp-custom.php)

<?php 
add_action("plugins_loaded","bpdev_init_sm_mode");
function bpdev_init_sm_mode(){
if(is_site_admin())
remove_action("wp_head","bp_core_record_activity");//id SM is on, remove the record activity hook
}
?>

Thank you.