If they weren't able to find an excuse to get upset and moan, they'd get upset and moan about that as well.
Face it, there are people that are determined to be miserable. It's fairly easy to avoid them in my real life - both in personal and working relationships. It's a shame that they can't...
There really are some proper miserable ***** who'll moan about anything and everything. I pity the people that have to deal with such unnecessary negativity on a daily basis.