Kakek,
Markit is, how can I best put it, a colourful fellow for sure, but as someone once said of Donald Trump, I don't like him, I didn't vote for him, but that doesn't mean he is wrong about everything.
Putting a lease in place which gives you an unquestionable legal right of abode for the property is very sound advice . It is not expensive and protects you (and your heirs) from all manner of adverse outcomes beyond a hypothetical breakdown in the friendship between you and the nominee.
I have witnessed both successful and failed nominee agreements, and the common thread that seems to lead to failure is extreme financial distress on the part of the nominee. It takes uncommon strength of character to let yourself drown when a lifeboat is bobbing beside you just meters away even if it belongs to your friend.
Let us however simply accept that your friendship with the nominee as sacrosanct and presents no risk .
Let us assume that you have taken steps to ensure there is no risk should your friend (God forbid) pass away or become incapacitated, that the house is left to you (giving you 1 year to find a new legal owner) or that your friends heirs are willing and financially able to pass up owning a very valuable property on the basis of a generally considered illegal nominee agreement that they were not party to.
Let us now assume the Government does not decide to intervene as they indicated the might back in 2015 when the Agrarian minister triggered the so called nominee crisis by declaring that they would systematically and proactively cross reference ownership, tax and residence information to work out the relationship between the person staying at a property and its rightful legal owner. In such cases where they found a nominee relationship, they proposed they would tear it up. I don't know that they ever followed up on this, I suspect not but who is to say this may be proposed again in the future.
If all of the above assumptions are true then you will be just fine. If not, well then only you can determine the impact on your future.
Just my penny's worth.
All the best & Happy New Year