Precisely. People fails to understand that.If japan and taiwan develop nuclear weapon, all nation will follow including iran, saudi arabia, Indonesia, and many other countries.US nuclear hegemon will be threatened because if japan and taiwan has nuke, then they doesn't need protection from US. US will be useless in asia pacific and no more superpower status.US conventional arm sales will be decline too.
Security selling is US's primary business. If countries like Japan, SK or TIOC get nukes, ba bye US.