TW is still thoroughly infiltrated by PRC intelligence, if there's credible hint they're moving from nuclear latency/threshold to actual nuclearization (PRC redline), the relevant facilities would be destroyed - no need for PLA boots on ground or telescoped build up, every inch of TW is within 10 minute strike of mainland based ordnances. TW nuclear turnkey potential isn't as fast as PLA rockets/bunker busters.
Unmentioned aspect of US axing TW nuclear program in late 80s, was CSIST / INER (Taiwan nuclear program) was already monitored by PRC intelligence and post Nixon normalization US intel cooperated with PRC intel to shut the program down. Unwritten between the line is PRC, having closely monitored TW program would have probably nuked TW first if US didn't compel TW to end the program. US Inspection / IAEA went in the dismantle the program, no doubt verified by PRC intelligence, it's unlikely TW can rebuild to nuclear turnkey faster than PRC can mount an invasion. And realistically TW can't fend off a PRC invasion without US involvement, and if US involves to assist TW nuclearizing then TW going to get nuked, and US + PRC will stare down MAD.
Unmentioned aspect of US axing TW nuclear program in late 80s, was CSIST / INER (Taiwan nuclear program) was already monitored by PRC intelligence and post Nixon normalization US intel cooperated with PRC intel to shut the program down. Unwritten between the line is PRC, having closely monitored TW program would have probably nuked TW first if US didn't compel TW to end the program. US Inspection / IAEA went in the dismantle the program, no doubt verified by PRC intelligence, it's unlikely TW can rebuild to nuclear turnkey faster than PRC can mount an invasion. And realistically TW can't fend off a PRC invasion without US involvement, and if US involves to assist TW nuclearizing then TW going to get nuked, and US + PRC will stare down MAD.