I would be surprised if he tried to sue them. There would be no sense in doing it as a PR stunt, like he is doing with the M7. He would need a tangible and positive result from suing the makers of TTATT. Either force them to reinstate him and his footage or --if/when the film is released and makes money-- demand a cut of the revenue.
It wouldn't make sense to sue them in Croatian court; he would need to do it in a more sensible venue. And that opens him up to discovery, depositions, and cross examination. I don't think there is a half-measure here. In order to have a chance --however small-- of winning, he has to do it legitimately. And I think that the only possible outcome would be that he loses, and that the trial potentially provides years of additional material to pummel him with.