Simply, he works in a position that is deemed public. His views are in the public eye. His (alleged) views are illegal. This is in most cases a reason to be arrested. Which in turn, in most contracts, in most job - public profile or not, particularly if it could bring his employers into a position of disrepute, is gross misconduct. This usually results in employment termination.
It has nothing to do with him being a footballer and therefore not having a right to offend, Many non famous, non footballers have been charged for similar insults. It's deemed discriminatory. Most discrimination is deemed illegal. That's not a bad thing.