He can call you a bad staff or a terrible staff it's his opinion if he thinks you are a bad staff member. Of he called you a shit staff that could be disrespect. You cannot when someone for their opinion on your staffing ability unless they use disrespectful words and name calling etc. The warning is technically false.
Saying you are a bad staff is still an opinion it's stating what he thinks or has heard which can influence his opinion into saying or thinking your staff abilities are bad.

He can call you a bad staff or a terrible staff it's his opinion if he thinks you are a bad staff member. Of he called you a shit staff that could be disrespect. You cannot when someone for their opinion on your staffing ability unless they use disrespectful words and name calling etc. The warning is technically false. Saying you are a bad staff is still an opinion it's stating what he thinks or has heard which can influence his opinion into saying or thinking your staff abilities are bad.