Accuracy. Using carbon dating for things that long ago gives you only a rough idea. Counting tree rings is precise, but tree ring chronologies are relative, unless they can be continued to the present or anchored to an event with a known date. These researchers did the latter, using a global and well-dated Miyake event.
The innovation is to find traces of a global cosmic-ray event with which to connect the dating of objects in one local area, Greece, where the dendrochronological data is not continuous, with those in far away local areas, for example England/Ireland, where we have continuous dendrochronological data
They do not believe Jews have any right to national sovereignty in their own land.
No - they just don't happen agree with them on the question of whose land it is.
You don't have to agree with their historical reading of the situation, of course. But it's really quite straightforward and simple, really. And if people are firing rockets at you -- it's probably best not to invent outlandish and unreal explanations for why they're doing so.
In any case -- pretending that the rest of the world obviously and unquestionably accepts the idea that this is all "Jewish land" (now or in 1947) -- or that if they don't, it's because the simply hate Jews, or won't accept the idea of Israel existing in any form -- definitely isn't helpful.
(And no, I'm not justifying or "explaining" the firing of rockets at anyone - please don't go there).
Whatever the reason is, it doesn't matter and you shouldn't bite on that hook. "They are evil and endangering our homeland so we are just in exterminating them" is Nazi rhetoric no matter who it comes from.
For whatever reason most people don't get that. I came to live in Germany around 15 years ago during the economic crisis and was pretty shocked that it was normal to say in public that Greeks are lazy. I couldn't understand the difference between that and "Jews are evil" and similar rhetoric that led to the Holocaust. And that in the country that should've learned something from the past. This time around I am not surprised they are fully behind this genocide simply because it's more convenient to look the other way.