On Twitter, Edward Pentin is stating that the "organizers arranged the whole thing without informing" the chancery or archbishop. This may be what he has been told from them.
First, no cardinal, no bishop can ban the offering of Holy Mass according to the traditional rite. However, a bishop does have the right to refuse another bishop entry into his diocese without his permission. At the rank of Cardinal, this is different; Cardinal Burke needs no permission to enter any diocese as he is a, Cardinal. The complication comes in with Zagreb's archbishop also being a Cardinal.
If the organizers did not advise the chancery, that was their mistake. It was imprudent and foolish.
The Archbishop of Zagreb, however, has acted inappropriately and needlessly created an ugly situation that did not need to happen.
There is a new phrase in Rome, and Cardinal Burke has become a verb.
He was "burked" and now so too, has the Mass.
The Archbishop of Zagreb owes Catholics an explanation and Cardinal Burke, an apology.