My son was suspended from a management position and was told they couldn't tell him why

someone must have complained, however,they refuse to tell him the reason,they say it is to protect the accuser

Legally a place of employment cannot terminate one of their own employees, be it suspension or firing, without informing them of what they did wrong. They are however allowed to protect their own employees by keeping their identities anonymous. Your son should get a lawyer to help him explain this to the company and find out what he did wrong so that he can be sure that it doesn't happen again.

I've had this done to me many times. It was not management positions but still it's the same thing. I don't know if it is in fact illegal for a company to do this. I wish I knew for sure, but a lot of companies are like that!