Last year, I was on a flight where BF boarding was held back while UA tried (unsuccessfully) to fix one of the seats (stuck in recline). I usually wait until BG1 is nearly done before getting in line anyways so it wasn't a big deal. In your case, it's lame that the catering was delayed but I'd look on the bright side and be glad that UA parallelized the catering and the boarding instead of making everyone wait.