I think it is to do with EU law.
We are not officially allowed to give you alcohol to take off so this crew member was correct.
We can't even sell tax free alcohol on EU flights either. i.e. there are no tax free sales of alcohol or cigarettes on flights within the EU and I think this may be linked as these will be tax free bars but for the consumption on board only.
Obviously if you take off a small bottle of champagne without us realising!!
no one will be any the wiser in most cases!