up the chain. Just 'cos the local manager has a prejudice/problem with bikers stealinhg petrol doesn't mean that upper management will support action they take that harrasses genuine customers; especially if you threaten any sort of protest/boycott. This tactic has worked in the past for supermarket stations too.
But...without wanting to reopen that debate....take the lid off first - at the very least it is impolite to wear it whilst paying; and the staff there who do face the potential of being robbed and on the receiving end of physical violence should not have to hope that you're intentions are fine despite your hidden identity. And, yes, I would say the same thing about people wearing hoodies/caps and face scalves. And just becuase them and burkah wearers may get away with it, isn't an excuse for bikers to do the same (IMO).