they can't , they scare , they don't want to ......and to make matter worst even if they change their mind now ....it no use . their economy style can't withstand heavy economic consequence if they openly counter US via sending weapon , set up military base ... use military power to protect someone US/west hate like that.China should offer military bases to countries with their full consent, to protect them from aggression from the United States. The US strikes the base? Than you have pretext to blockade Taiwan.
their population also show no sight of willing to accept heavy economic consequence for the end game greater good