I think you need to spend some quality time with a good dictionary.
An oxymoron is a self-contradiction - something like "binary options liquidity provider" or "100% guaranteed profitable, no losses ever managed account".
Requiring keeping documents for 5 years does not mean the same as requiring destroying the docs at the end of 5 years.
If there is no requirement to keep documents at all (still highly debatable based on customer due diligence including "when establishing a business relationship"), that still does not mandate destruction of documents of failed applicants.
You have not provided a single piece of evidence even hinting at the existence of any legal or regulatory requirement anywhere regarding when or if Mayzus must ever get rid of your documents.
Instead, you didn't even bother to double-check to see if the regulations behind that AML summary you quoted includes someone in your category or not.
If you do hire a lawyer, I'd love to see a proper legal opinion on those UK regs instead of more bluster about your tunnel-vision version. Of course, a video of you attempting to argue this in court by yourself with nothing but a short summary pulled off a single web page would be more entertaining.