Integrate SearchWP and Jetpack Infinite Scroll

gistfile1.php

<?php

// Jetpack infinite scroll does it's own WP_Query, so we need to hijack it at runtime
function searchwp_infinite_scroll_query_args( $query_args ) {
	if( class_exists( 'SearchWPSearch' ) ) {
		$query = get_search_query();
		if( empty( $query ) ) {
			if( isset( $_GET['query_args']['s'] ) ) {
				$query = sanitize_text_field( $_GET['query_args']['s'] );
			}
		}
		if( !empty( $query ) ) {
			// piggyback the submitted query args
			$searchwp_args = $query_args;

			// customize for the SearchWP search class
			$searchwp_args['page']        = $query_args['paged'];
			$searchwp_args['terms']       = $query;
			$searchwp_args['engine']      = 'default'; // search engine name
			$searchwp_args['load_posts']  = false; // only want post IDs because we're going to send those back
			$searchwp_args['order']       = 'DESC';

			// fire the search
			$searchwp = new SearchWPSearch( $query_args );
			$hijacked_IDs = $searchwp->postIDs;

			// overwrite the original query vars to be what we want as per SearchWP
			$query_args['post__in'] = $hijacked_IDs;
			$query_args['orderby'] = 'post__in';
		}
	}
	return $query_args;
}

add_filter( 'infinite_scroll_query_args', 'searchwp_infinite_scroll_query_args' );

// also ensure the titles are highlighted as well
function my_searchwp_highlight_title( $title, $id ) {
	if( class_exists( 'SearchWP_Term_Highlight' ) ) {
		$query = get_search_query();
		if( empty( $query ) ) {
			if( isset( $_GET['query_args']['s'] ) ) {
				// Jetpack
				$query = sanitize_text_field( $_GET['query_args']['s'] );
			}
		}
		if( !empty( $query ) ) {
			$highlighter = new SearchWP_Term_Highlight();
			$title = $highlighter->apply_highlight( $title, $query );
			unset( $highlighter );
		}
	}
	return $title;
}
add_filter( 'the_title', 'my_searchwp_highlight_title', 10, 2 );

On lines 29-32, you set something and then immediately unset it:

            $query_args['orderby'] = 'post__in';
            if( isset( $query_args['orderby'] ) ) {
                unset( $query_args['orderby'] );
            }

Is there a particular reason for that?

@benlk I have no idea what I was thinking there, removed!