Such glitch are mostly not addressed well in terms and could have brought some lawsuits but casinos surely would have an upperhand on it considering its from a Malta. As I looked for Superbet, they seem to be a huge gambling platform out of Malta with thousands of employee. The compensation money they gave would be a small part of their monthly profits so they can afford it. If it were some smaller casinos, they wouldn't have respected the wins.
It's a rare show of generosity by the casino. The respect for rare or once a time glitches by reputed casinos is not rare but paying everyone who repeatedly misused the glitches that was existent for a long time means either the amount is smaller compared to the profit they are making.