Well, sounds good but definitely, they only intended for promotion not accepting Bitcoins or other cryptocurrencies. Well, maybe people asking now how come that cafe looks like there are many logos on crypto but the whole concept they did not accept bitcoin/cryptocurrency as a payment. Indeed, that was good since OP says it is illegal to their place to use bitcoin and through that cafe still there is the presence of cryptocurrency even their government prohibited on it.
For promotions it will help awareness but how can they attract when the government is against the sage of this system, it's not making sense
not unless they have something behind this promotions, not really care about anything but just to help reaching people around the place to
learned and be attracted inside crypto.
It may work if they play the educational role seriously, as giving small tidbits about the whole thing, in coasters the tables, signs, video screens, etc; to let the public know. Eventually politicians will attend the cafe to find out, and perhaps later turn the anti bitcoin stance.
Perhaps a map somewhere: Did you know? Showing in green the countries where its legal (ie. the wikipedia
legality map).
"Petition your politician today" with their mail addresses, etc.