Disables jpg jpeg png gif image upload to Amazon S3 from WP Offload plugin on the site of the multi site network where it is activated

gofas-disables-s3-uploads.php

<?php
/*
Plugin Name: Gofas Disable WP Offload S3 on this site
Plugin URI: http://github.com/deliciousbrains/wp-amazon-s3-and-cloudfront-tweaks
Description: Disables jpg jpeg png gif image upload to Amazon S3
Author: Gofas Software
Version: 0.0.1
Author URI: https://gofas.net
Network: False
*/
class Gofas_Disables_S3_uploads {
	function __construct() {
		add_filter( 'gofas_pre_update_attachment_metadata', array( $this, 'pre_update_attachment_metadata' ), 10, 4 );
	}
	function gofas_pre_update_attachment_metadata( $abort, $data, $post_id, $old_as3cf_item ) {
		$file      = get_post_meta( $post_id, '_wp_attached_file', true );
		$extension = is_string( $file ) ? pathinfo( $file, PATHINFO_EXTENSION ) : false;
		if ( is_string( $extension ) && in_array( $extension, array('jpg','jpeg','png' ) ) ) {
			$abort = true; // abort the upload
		}
		return $abort;
	}
}
new Gofas_Disables_S3_uploads();