You are right. That pact SPECIFICALLY does not require anyone to do anything at all, but does contain provisions about working towards specific goals.
However, in game you cannot make specialized custom agreements. You do not get to stipulate article by article what the Mutual Defense pact ACTUALLY does or tries to do. I've not read NATO treaties, but I seriously doubt that that treaty is so vaguely worded on the issue of military assistance. I could be wrong (and have been when making assumptions, but hey let's toss those dice!

).
Nevertheless, the point remains that the game describes (or described, not sure if it still does, will have to check) mutual defense treaties as GAURANTEED DEFENSIVE HELP IN TIME OF WAR. That article is very unambiguous. So again, why are we bringing up examples from treaties that have no basis within the game we are talking about?
I did see the term Mutual Defense in the title, but not within the actual posted article. Also, To me article 2 did imply that military assistance was expected. No one is foolish enough to think that Taiwan could force the US go to war with someone they did not want to. But I don't see anwhere that states that it is okay for the US to sit back and do absolutely nothing.
It seems prefectly clear that assistance (including of a military nature) was to be expected and that if one or the other party were not being 'assisted' the treaty would be, by default void. Certainly if China attacked Taiwan and the US did nothing but tell them which direction they were going to be completely overrun from and then wished them good luck, it would be within Taiwan's right to believe that the US was not living up to the agreements arrived at in the pact, making the pact void.
At the very least they would probably feel betrayed by the US, not trusting them much ever again (imho). That was what I was pointing out. If the agreement itself is unable to be dropped at will (without dropping every other agreement you have), then the terms of the agreement as stated in game, not between Taiwan and the US, should be mandatory as well.
Jeez sorry that took so long. Really the point is about game mechanics (since game mechanics don't allow the flexability of a real world treaty). I am sure there are many Mutual Defense pacts throughout history that specifically require one nation to defend another in times of war that could be used as counter-examples but we don't get the flexability in-game to define treaties case-by-case, so I believe the Mutual Defense treaty should simply do what it states it will within the game.
There are already mechanics for someone to choose to defend/aid someone else they have good relationships with that are analogous with the treaty that has been cited previously. A non-binding mutual defense pact seems like empty (except perhaps, of frustration) fluff in a game like this. To me, it seems redundant and misleading.