Lots of bull**** being spread here
This is not about human rights, minority rights, religious rights, racism or even very much about the law. The latter only in the sense that BA has to be prepared to pay up. It's about running a company and minimising the threat to that company's existence.
Even if there's zero hard evidence against this pilot which would stand up in court, BA top management has to judge the risk and act accordingly. If they suspect there's a one in a hundred chance that this guy is a threat, that creates a level of probability of disaster that would never be permitted in an aircraft component. He had to go.