Since the flag of Saudi Arabia is regarded as a religious symbol, it may not be flown at half-mast (for mourning) or upside-down (as a distress signal). So, how would a Saudi ship at sea, for example, express mourning or distress?
Ships at sea generally don’t fly flags at half-mast, not least because the flagstaff is generally too short to make this noticeable.
As for distress signals, the practice of inverting the national flag is not a universal distress signal. There are many countries whose national flags are the same when inverted - e.g France - or nearly the same - the UK. And there are others whose national flags, when inverted, become the flags of other nations - e.g. Poland and Indonesia. Plus, ships have many different, and more recognisable, signals of distress available to them - maritime signal flags, distress rockets, a voice or morse radio message or a radio beacon. And most of them are detectable at greater distances than would be possible with an inverted national flag.
International Code Signalflags. There are a number of different flags and combinations of flags used for specific circumstances.