That is true. Although if China's strategy was by choice or necessity a stand-off one, it would give the US time to organise a response to convince China to stand down, whether by showing sufficient resolve and force (Beijing then tries to claim it was just proving a point to dissuade UDI), or by breaking a blockade and resupplying Taiwan.
There are some interesting power political dimensions at play in this game of chicken.
If such a crisis ever did emerge (specifically most likely it would be a Taiwan move to de jure independence), it would essentially be a function of each side's perception of resolve and power of each other.
The goal of each side would be to dissaude the other from acting.
For China it would essentially be to deter the US from getting militarily involved, for the US it would essentially be to try and deter China from military responding to Taiwan's move to de jure independence.
It goes without saying that if both actions by China and the US occur, (US military involvement and China militarily responding) the end result is a major westpac conflict between two nuclear armed powers.
... At this stage I'm still not sure where the fulcrum of power lies. Everyone is aware of the priorities each side sees in Taiwan, but the degree of sacrifice that each side is willing to lay down for Taiwan is still a question.
I am of the belief that the nuclear factor may be the most significant -- specifically, the size and the survivability of the Chinese nuclear deterrent might cause China to more credibly be able to threaten the US with MAD if not near MAD with the challenge of asking if the US wishes to make Taiwan a modern equivalent to berlin as a tripwire for nuclear annihilation, of course with the clear understanding that Taiwan itself is important enough for China to be willing to consign itself to nuclear apocalypse and to drag as much of the US (and the rest of the world) with it as possible, if things come to it.
In geopolitical terms, the goal would be to make clear to the US and the world that Taiwan ultimately is not a territory that is China is trifling with but something that they consider to be willing to sacrifice the entire world over if necessary, in the same way that the US would sacrifice the entire world if it was under attack in an equivalent manner.
Such a nuclear policy declaration of course would be made in a manner that "adjusts" but doesn't forbade the NFU policy, and would likely be made with the implication that attacks on key strategic facilities would be considered an attack against China's nuclear deterrent. I imagine such a declaration would only ever be made on the eve of perceived inevitable military conflict as well.
Of course, direct US military involvement might not necessarily be the only response -- the purpose of US power projection is to control SLOCs and maritime chokepoints, so it isn't impossible that the US chooses to avoid direct conflict and instead seek to commit a "distant water blockade" on China instead, essentially daring China to break the blockade and making conflict further away from the Chinese mainland.
Such a possibility of course will sought to be mitigated by China seeking to build up a powerful navy and air force to be able to project power as well and either seek to protect its own shipping and in turn test US resolve in those areas of blockade, as well as to further integrate itself with the world economy so that if a blockade on China does occur those other trading partners will vocally advocate for continued freedom of navigation of trade and commerce and energy and isolate the US and its partners, and of course eurasian economic and energy integration to complicate the US ability to dominate sea lanes.
Over the last few years this has basically been the major fulcrums and plays that I see the US and China essentially making.
Of course, unforeseen revolutions in technology might change each side's available options, but they're called unforeseen for a reason.
