Earlier quoted context omitted.
TW nuclear breakout window is long gone. The island is now thoroughly infiltrated by PRC intelligence. There is no opportunity post 90s to secretly start up a nuclear program without getting glassed by PRC first, and with full endorsement from every nuclear power who doesn't want to see nukes proliferate to mid-tier nations.
That’s a very optimistic take on PRC intelligence operations. Historically countries simply aren’t nearly as good at gathering intelligence as you might think. Further we don’t know what intelligence the PRC has gathered. If China believes Taiwan has nuclear weapons or the capacity to assemble them quickly, there is going to be very little change in rhetoric from China.
To your edit: any credible nuclear break out threat from TW would be taken out within 10minutes from PRC rocketry. Of all PRC redlines, the most serious are TW ones. PRC has fought with nuclear USSR and US over less important core interests while PRC wasn't nuclear. PRC will absolutely preemptively crush any TW nuclear efforts.