If a semicolon is being used as a symbol of mental health struggles or suicide survival, I am not labeling that person. The person who decides to get that tattoo is marking themselves. I know that some employers might take that as a sign of instability/increased health care costs or even unreliability. Being a person who struggles with such things, I do not personally think less of people like me.

Even someone surviving cancer should not announce it to a potential employer.
I'm basing this on unethical things I've seen and heard employers do.

The only part that is coming from me is this--I don't think using illness as part of your permanent identity is healthy. That part is just my opinion.