The Neturey Karta resoyim WERE at the Pro Israel DC rally. They were the only group of Palestinian nationalists that were there.
You don’t ask questions on the NK assuming there is any type of Torah based chesbon for what they are doing. Whatever they were 30 or 50 or 70 years ago (there is a difference between what they believed and preached in all those time periods), at this point in time, they no longer even bother claiming to be a Torah haskafa based group . They are Palestinian nationalists. Their website is pure militant Palestinian nationalism, their rhetoric is straight party line Palestinian nationalism, their references to Torah are only made in an effort to encourage Palestinian nationalism etc.
The Satmar Rebbe (Rav Yoel) was well known to have opposed making any joint efforts with non-Jewish anti-Zionist groups. As one close Talmid of his told me he was there when someone broached the ideas and The Satmar Rebbe emphatically answered “Chalila to do such a things!!!” I used to think that it was only because of what rotzchem most non-Jewish anti-Zionist groups are. I now realize another reason why it is such a terrible idea: Torah haskafa needs to be exclusively Torah based. Once you start making common cause with non-Jewish groups to advance an haskafic issue it is only a matter of time until that group will start having a heavy influence on you and your haskafa. Particularly when they are giving you money and honor like the NK receives. That is how and why the NK ended up what it is today