My question involves labor and employment law for the state of: Massachussets

I have a co-worker that just received a written warning on the basis that another co-worker was at the hair salon with the employee's father and the father made various comments about how unhappy the employee is, how the reviews are late and inaccurate, and in general how poorly the company is run from a labor management standpoint. The co-worker apparently reported this to management and the employee I am asking about received a written warning as a result - the first ever for her.

Is this legitimate? Can they issue a written warning on such a basis?