This solved my problem:

https://gist.github.com/rmorse/074db89682afa8501b15

	function sf_filter_query_args( $query_args, $sfid ) {
	  
			$posts_to_exclude = array();
			
			$args = array(
				'posts_per_page' => -1,
				'post_type' => 'grants',
				'tax_query' => array(
				    array(
				      'taxonomy' => 'program',
				      'field' => 'slug',
				      'terms' => array('youth-service-improvement-grants'),
				    ),
				),
			);
			
			$myposts = get_posts( $args );
			foreach ( $myposts as $post ) : setup_postdata( $post );
				$tags = get_the_terms($post->ID, 'person');
				
				if(!empty($tags)) {
					
					foreach($tags as $tag) {
						$tag_slug = $tag->slug;
						$tag_terms = array($tag_slug);
	
						$args = array(
							'posts_per_page' => -1,
							'post_type' => 'grants',
							'tax_query' => array(
								'relation' => 'AND',
							    array(
							      'taxonomy' => 'person',
							      'field' => 'slug',
							      'terms' => $tag_terms
							    ),
		                        array(
							        'taxonomy' => 'program',
							        'field'    => 'slug',
				      				'terms' => array('youth-service-improvement-grants'),
				      				'operator' => 'NOT IN'
		                        ),
							)
						);
						
						$my_person_posts = get_posts( $args );
						
						if(count($my_person_posts) < 1) {
							
							$myperson = get_page_by_path( $tag_slug, OBJECT, 'people' );
							
							if(!empty($myperson)) {
								$posts_to_exclude[] = $myperson->ID;
							}
						}
					}
				}
			endforeach; 
			wp_reset_postdata();
			
	        $query_args['post__not_in'] = $posts_to_exclude;
	        
	  return $query_args;
	}
	add_filter( 'sf_edit_query_args', 'sf_filter_query_args', 10, 2 );