Plastic is a hot issue at the moment- If some pressure / negative PR was applied, it would get picked up in the press, and I think you would find that the club- at that point- would bottle it.
Fans could easily get the bottle top and flask ban lifted. Just push the environmental angle- fans wanting to minimise plastic use and bring their own reusable bottles / flasks. Bring a few banners to the games- would get picked up in the media, and would expose the club for their cynical money...