What they don't like is the publicity.
Edit: but maybe not in Hungary. It's the bad child in EU.
At first the bank security department said no one will find it so it's safe and later when he pressed the issue as a dangerous leak they reported him to the police for "hacking and extortion". All the computers from his company got confiscated for investigation so he had to buy new computers and software to continue running his company. In the end he was found not guilty by the police investigation of his computers so the prosecution dropped the case (it didn't even go to court) and all his stuff returned after 6 months.
Source in Polish (sorry, there is no English source): https://niebezpiecznik.pl/post/glebokie-ukrycie-danych-w-pko... http://www.tvn24.pl/wiadomosci-z-kraju,3/haker-mimo-woli,132...
Bank spokesperson later explained that the files were "deeply hidden" ("głębokie ukrycie", he said it's an IT term, it's not) and only one person found them in 4 years of their existence there so it's not a big deal.
And in general misusing, testing, etc. a website is illegal without owners permission, there is now a small exception for acting in good faith but it's narrow, a bit strangely worded and it doesn't prevent stuff like above.
The European commission is currently threatening to remove Poland's voting rights due to the changes to the juridical system, but it will not happen as Hungary will veto.
I think they are on their own cultural axis somehow.
> Edit: but maybe not in Hungary. It's the bad child in EU.
The article suggests that they reported this guy to the police only after the info leaked out (or possibly was independently discovered by others) and made it to the press.
Scapegoating of non-malicious hackers isn't really anything new or unique to Hungary. It's a common reaction of IT-illiterates to people "cheating" on their systems everywhere.