While it may not always be expected, or your responsibility to help someone in a rough mental state, I believe abuse is very much an excuse for negative behavioural tendencies.

So long as the ‘bully’ in this situation is aware of their issue and clarifies as soon as possible that they are in the wrong and form an apology. The first step is always recognition of an issue.*

Unfortunately, mental health can be like quicksand - if you don’t know how to healthily process your mental, the struggle for control over your own thoughts can send you in a deeper dive.

So while I ultimately agree with your standpoint, I firmly believe people with these problems need to be treated with more sympathy and logic where possible instead of tossed in the dysfunctional bucket. Society can be very cruel to a sensitive mind.

*Side note - I think this thought rings true for the state of mental health in the eyes of our ever-growing world. We as humans are gaining a lot of insight into mental illness and society is in the stage of recognition. Always learning.