PHP コードが CSV ファイルから BOM を削除できないのはなぜですか?

<code class="php">function removeBomUtf8($s){
    if(substr($s,0,3)==chr(hexdec('EF')).chr(hexdec('BB')).chr(hexdec('BF'))){
        return substr($s,3);
    }else{
        return $s;
    }
}

setlocale(LC_ALL, 'nl_NL');
ini_set('auto_detect_line_endings',TRUE);
require_once(ABSPATH.'wp-admin/includes/file.php' );

$path = get_home_path();
$filepath = $path .'wp-content/themes/pon/testing.csv';
$content = file_get_contents($filepath);
file_put_contents($filepath, str_replace("\xEF\xBB\xBF",'', $content));

// Create temporary file
$tempfile = tempnam(sys_get_temp_dir(), 'csv_');
fopen($tempfile, "w");

// Process lines and remove BOM
$file = fopen($filepath, "r") or die("Error opening file");
while(($line = fgetcsv($file, 1000, ";")) !== FALSE) {
    fputcsv(fopen($tempfile, 'w'), $line);
}

// Move temporary file to original location
fclose($file);
unlink($filepath);
rename($tempfile, $filepath);

// Continue your processing
...</code>