It may not be Dassault, but disgruntled Swiss Air Force personnel who'd rather have the bigger, sexier, aircraft.
If it had been the work of a disgruntled officer one would think he would have leaked a document favoring the Typhoon not the Rafale. As for Dassault, I don't think they recruit agents. I was actually referring to the French intelligence services.
In any case it doesn't matter, here and to us, who did it and why. My point is to propose a course of action and purely for the intellectual challenge it presents.
For anyone who may have an interest to uphold the Gripen decision it might be possible to:
First, argue convincingly the irrelevance and fallacy of the report and its omissions.
Second, have someone note the convenience of the leak to the French for its timing, its carefully selected content not only for the editing but also in the face of presumably hundreds of documents of contrary content (if there really are publish some)
Third, have someone start insinuating an intelligence connection.
Fourth, leak news of an ongoing investigation (real or not) into the involvement of an unspecified foreign intelligence service.
Fifth, of course conduct the real investigation to find the leak and fix it.
If later on more leaks follow of the same sign it will just prove your point. A genuine new leak might help identifying the information path and the source.
If no official accusation is made to the French they couldn't respond officially (one doesn't yell their innocence without being accused first) and so it shouldn't compromise relations.
And yes, yes, of course it is pretty lurid. But it's always better than having disloyal civil servants or foreign countries dictate policy by manipulating public opinion. Also you can modulate the strategy according to your tolerance level for filth. I'm sure the professionals can come up with better variations.
Now, all of this might seem to somebody like a smart thing to do; actually it isn't. It represents a disruption of democracy. The best defense against such foreign interferences would be to prevent them by improving security, discouraging treason and foreign operations in the first place. These however do require raising the level of awareness and raising the risks for the perpetrators. So the proposed strategy is really a short term fix.