Fortunately Art 52 is massively non-specific
I would be amazed if somebody briefing from GFS got done; the data from GFS is no more and no less random than the data from the UKMO. But - depending which website you use - it's potentially far more complete and that would make a very compelling pro-safety argument; a good lawyer would make mincemeat of the other side by drawing attention to the data which the UKMO witholds in order to make money.
But not a lot of people know about Art 52; I am sure that most UK PPLs really do believe that you have to brief from the UKMO to be legal. A bit like carrying paper charts - no law (in the UK) requiring that either.