I know nothing about the organisers of the march, but if there are links to far right or far right views then it absolutely affects his position at the club.
He's a coach, a teacher and influencer of kids who come from very wide and diverse ethnic backgrounds, if these are his "personal beliefs" then that impacts on his ability to teach/coach and treat those he's teaching.
Here is a selection of the West Ham U18 squad he coaches:
Anang, Sanneh, Jinadu, Dalipi, Okotcha, Belie, Nsumbu, Adu, Appiah, Baptiste, Mhassani, Khouri, Kileba, Mingi, Nebyle, Ngakia.
Just wondering how they and their parents feel that someone who openly and passionately holds the "beliefs" (assuming that the group is indeed affiliated with ultra right wing beliefs) that he does?
He is entitled to his beliefs (if legal), just as everyone is, but there are serious ramifications for the club, being "PC" or not is a smokescreen to the real issue of whether he has the fundamental ability to carry out his role without bias or prejudice. West Ham should also have serious concerns on whether this affects their ability to attract young players to their academy in the future. Will the kids currently there wish to remain? This type of position is very important, just as it is in schools etc. It's his function at the day-to-day level that is surely what is compromised not whether it's "PC" or not.
There are obvious financial ramifications too, with sponsors and potential sponsors unwilling to have their brand associated with the club.