Tu.144: there is no reason to believe that there was something illegal about this flight
No at all, luckily EASA stands for "European Aviation
SAFETY Agency".
Though, I am surprised to notice so many low fuel situations with European carriers. Despite all their [JAA/EASA] additional, would be painstaking, regulatory (and questionable) requirements, thorough ATPL written tests, mandatory English proficiency tests, etc., etc. Maybe they lack some simple common sense.