Something like this is always displayed in public for a reason. For various reasons, I see it as a way for them to raise awareness of bitcoin and encourage people to thoroughly research it in order to avoid becoming a victim of its use. They are centralized banking services, and they cannot do so to their own detriment. Furthermore, portraying this in public encourages people to seek out more information about what they've been asked to study, which could serve as another way to attract people interested in bitcoin.
This could also be done to mildly spite the central bank, we all know what and how the banks have been handling our money, the inflations that have been going on for several years now, which as a result have devalued our fiat currencies, causing the prices of things to become really high..
Doing this could mean several things, it could mean a digitalized form of protest against Central Banks, reminding them that there is a new and better currency in town that they(central banks) have no control over , and that they should study bitcoin and know that their days are numbered - and at the same time, this is also creating bitcoin awareness to the general public, for those who are not aware of what bitcoin is all about, it's a good advice for them to go and study bitcoin.