Taxonomy does not work with multiple select - sphinxsearch_common.inc

I have been testing this module with taxonomies and have found that for a free text taxonomy it works but only because array_filter function always returns null, when you use a multiple select taxonomy the $request_options[$terms_key] will be an array of tids anyway, but when it runs through the array_filter function it returns null so it always goes into the if statement never the else which is where you want it to go when you have an array of tids in $request_options[$terms_key]

Current Code in sphinxsearch_common.inc (line 301)

$tids = array_filter(array_map('intval', array_map('trim', explode(',', $request_options[$terms_key]))));
if ($request_options[$terms_key] != implode(',', $tids)) {
    // Request came with a comma separated list of terms.
   $terms = sphinxsearch_taxonomy_decode_typed_terms($vid, $request_options[$terms_key]);
}
else {
   // Request came with a comma separated list of tids.
   $terms = sphinxsearch_taxonomy_get_terms($vid, $tids);
}

My change code in sphinxsearch_common.inc (line 301) that seems to work, which be right or wrong, I do not understand the full implications of this change at this point to the rest of the search.

//$tids = array_filter(array_map('intval', array_map('trim', explode(',', $request_options[$terms_key]))));
if (is_string($request_options[$terms_key])) {
    // Request came with a comma separated list of terms.
    $terms = sphinxsearch_taxonomy_decode_typed_terms($vid, $request_options[$terms_key]);
}
else {
    // Request came with a comma separated list of tids.
    $terms = sphinxsearch_taxonomy_get_terms($vid, $request_options[$terms_key]);
}

I'm pretty new to drupal and php so apologies if I haven't explain it properly.