With all due respect, that article is relatively useless. Until someone controls (in their stats) for income they're not going to come to any useful conclusion about the influence of ethnicity on HE achievement.
I'm surprised nobody noticed the absurdity of positing that 'ethnic minorities under-achieve in HE' -> 'ethnic minorities often have problems with funding, commuting, family etc, due to their relatively low-income position in society, that impact upon their performance and the quality of their experience' -> 'therefore it must be institutional racism'.