It is not clear that Al Madinah used unqualified teachers. The report says that they were not experienced, which is a different issue.
And it absolutely is caused by the school being Islamic. People were more focused on ideological Islamic purity than education.
This has happened before.
New Monument School in Woking (which like Al Madinah had mostly Muslim pupils) was the subject of a takeover campaign by Islamic governors, who forced her out in a drive to make the school more Islamic.
They destroyed the school, which like Al Madinah was put into special measures, having been rated 'Good' previously, with the head acclaimed in Downing Street. The school was put into special measures in 2006, and again in 2009.
In the case of Al Madinah, the whistleblower was the former head, who, not unlike the head of New Monument, left his job as a result of governor actions, after again, not unlike the head of New Monument, previously (apparently) running a good school.
www.theguardian.com/education/2013/oct/22/al-madinah-headteacher-admits-whistleblower-cutts-mckayckay
The Guardian tells us that Al Madinah is a 'devasating blow to Gove', whereas it had nothing at all to say on New Monument, which was reported only by The Telegraph, Daily Mail and local press, despite the £400k payout for the head, who had to give up her home and take a job as a care assistant as a result of the campaign.
www.telegraph.co.uk/education/primaryeducation/7664621/Erica-Connor-driven-out-of-my-own-school.html
British Pakistani culture is very different from British culture.
In the area of New Monument School, the victorious candidate at the last election, one Mohammed Bashir (Liberal Democrat) and his extended family forged votes, getting votes from the dead and deported and was found guilty of electoral corruption in the last local elections. www.getsurrey.co.uk/news/woking-election-result-thrown-out-5379770
His replacement in the re-run election, experienced local politician Norman Johns, finished a very distant last (fourth behind UKIP), while the Tories, the only party to nominate a Muslim candidate, went from third to first.
Pakistanis do many things differently, some better, some worse, but supposing that Al Madinah tells us anything about unqualified teachers is absurd.