I like Kneecap but it's literally well known that it's a criminal offence to publicly support or endorse a proscribed terrorist organisation.
It's not a crime, however, to voice support for the Palestinian people, and it's possible to do one without the other
I'm a bit of a free speech absolutist, so I personally don't give that much of a shit what anyone says. Individuals are entitled to their views whether I like it or not. However, this is edgelord, publicity seeking behaviour (and has been successful!).
I don't think you can claim to give a fuck about women and children and then be flying the flag for Hamas, figuratively or otherwise.
Also, 9.1 million people in Syria are on the brink of starvation (if not already there) due to the actions of the EU (among others). I'm not usually one for whataboutery but it seems very odd the obsession with Israel and Palestine while many more staving victims of war, exacerbated (or, indirectly created) by the same agents involved in Israel/Palestine are largely ignored elsewhere.