Exclude entries within a taxonomy term from SearchWP's search

functions.php

<?php

function my_searchwp_exclude( $ids, $engine, $terms ) {

	$entries_to_exclude = get_posts(
		array(
			'post_type' => 'any',
			'nopaging'  => true,
			'fields'    => 'ids',
			'tax_query' => array(
				array(
					'taxonomy' => 'category',
					'field'    => 'slug',
					'terms'    => array( 'category-1' ),
				),
			),
		)
	);

	$ids = array_unique( array_merge( $ids, array_map( 'absint', $entries_to_exclude ) ) );

	return $ids;
}

add_filter( 'searchwp_exclude', 'my_searchwp_exclude', 10, 3 );