Subway didn't actually do that though. Some franchises in India have lamb and chicken instead of pork and beef, and some have no meat options at all. 185 franchises in Muslim neighborhoods in the UK (out of over 1500) serve only halal meat, which means by definition they don't serve pork.
Those were just business decisions based on local preferences. You can't get pork at a Subway in a 90% Muslim neighborhood because there isn't a demand for it, not because people forced subway to stop selling it.