Mr Dybowski's claims of harassment and direct discrimination related to his religious and protected beliefs were dismissed, with the judge saying the school could exercise a degree of control over how beliefs "manifested" in accordance with its values.
The day after the training event, the headteacher at The Bishop of Llandaff High School told Mr Dybowski he did not want those views shared while he worked at the school, after "a number of staff expressed concern".
The headteacher reminded him of social media guidelines and the Education Workforce Council (EWC) regulations, explaining that expressing his views in a public forum could potentially harm students or staff, especially given the school's diverse community and values, the tribunal heard.
Mr Dybowski told headteacher Mr Belli that he had "regularly expressed" such views on social media.
The judge said it was "reasonable" for Mr Belli to have become very concerned and concluded that he could not trust that Mr Dybowski would refrain from inappropriate discussions with pupils.
