This is a choice of venue and is considered non-free by many debian-legal contributors (including me...). In a nutshell, this choice of venue discriminates against people who live far away from Santa Clara County, California, USA and thus fail DFSG#5. Those people can be forced to travel around the planet in order to defend themselves in a dispute raised by the copyright holder.
I am not at all convinced. First, I wonder if this choice of venue is legal. You must be aware of the fact that any condemnation of US tribunal cannot have any effect outside of the U.S.; so if this person leave far away from the U.S, he can simply ignore any decision of an U.S. tribunal as long as he does not comes to the U.S. If someone is sued it is always very inconvenient for him whether he lives on the U.S. or not. In some case this choice of venue if even more avantageous for someone not living in the U.S. since only a U.S tribunal can sue him and the decision of this tribunal has no effect in his country.
Anyway even without this choice of venue, I do not see anything preventing Adobe from suing someone in an U.S. tribunal; so the argument is in my opinion fundamentally flawed. The only thing that it really restrict is suing Adobe in another country; but that does not seem to be a problem.
Olive