Legally a person cannot be made ‘stateless’ - unless they have an alternate citizenship to fall back on, you cannot revoke theirs, no matter how reprehensible they are. The ISIS volunteers from Europe weren’t made stateless, just very dead or arrested
Doesn't really matter either way, he's not coming back, the way the war is going he'll probably be blown up at some point, and if he does survive he'll be arrested. His nationality is basically not relevant.
I was going to write that this seems like a shitty paper, with the unprofessional writing and typos. Then I saw it referenced a Mirror article. Turns out they lifted much of the wording from the Mirror, but not all of the punctuation. So they took shitty writing and made it worse.