For just one reason, being chief designer, Mike Coughlan has a huge infuential position in introducing ideas from Ferrari.
Also, Mclaren leap froging from no win in 2006 to being the most competitive car of 2007 should make the jury to get convinced that Mclaren indeed benefitted from Ferrari's documents.
It is better Ron Dennis gracefully accept their wrong doings and get himself a lighter sanction. If nott from FIA , it may come form the civil proceedings.
The penalty wil be huge if they are found guilty because it was accidentely found to be in possesion of such documents. And if not found they might continued to have those documents and used it for their purpose.
If F1 circle so for taken the spy scandal lightly, better they wake up.