You can use this function meantime (performance sucks anyway):

// 32-bit zero-filled right-shift
function zrsh($a, $n) {
  if ($n <= 0) return $a;
  $b = 0x80000000;
  return ($a >> $n) & ~($b >> ($n - 1));
}

There appears to have little interest in this operator within
almost 10 years, so it seems like a won't fix.

If anybody is still interested in this, please pursue the RFC
process[1].

[1] <https://wiki.php.net/rfc/howto>