Ill health, like tiredness, is no one's fault. Ill health may lead to a mood change that might otherwise be misinterpreted.
When someone is in a bad mood those around are quick to ascribe it to illness. Code 10/10 signals this directly. There is no longer any need to speculate as to why someone is in a difficult mood.

Once the condition has been signalled, those around will want to show some consideration in their behaviour (tea and sympathy).

This code may be abused when a person comes to use it as an 'excuse' for general bad temper. In the end this does not matter very much. If someone wants to state a false reason for the bad temper, it destroys the whole purpose of being bad-tempered (to bully, etc.).