As a university member I can get past the paywall and I'm reading it now. Not my field but it's pretty obvious that the Telegraph is massively overselling the results. The sample size is 38 people, split into two groups of 19 -- at the minimum for a statistically significant sample, for starters -- and the authors throw in a huge number of caveats all of which are overlooked by the Telegraph: "the present work does not address several key questions..." being the most revealing.
The main claim of the paper is that there is a good indication that there is a biological mechanism that is involved in "ideological commitment", and that this can be manipulated. But the work is preliminary, acknowledged as so, and intended primarily to "[open] the way for researchers to not only
describe the biological mechanisms undergirding high-level attitudes and beliefs, but to establish causality via experimental intervention."
Whether this can be established by zapping brains with magnetic fields and then giving 38 people texts either praising or criticising the US, I can't say. I'm a little sceptical to be sure but I don't think it should be dismissed as pseudoscience so quickly.