He hasn't "won a block" in the sense most people will understand it. He has interim relief which means that his removal has been delayed for a very short period of time. The reason for that, according to the article, is that he says he has evidence that he should be exempt from the scheme. If he fails to produce it, or (more likely) he produces it and the Home Office say it's not good enough, then he is back to square one.
The govt will have been anticipating these types of challenges and their arguments will have been readied in advance.
I don't know why they would choose an Eritrean national to guinea pig it, since Eritrea is an absolutely appalling pit of human rights abuse and most applicants are successful. Either there was no discretion as to nationality applied, which would make sense, or it is an active choice by the govt in order to dispel challenges based on risk of refoulement.