How much life is there left in those F-16A airframes?
Were they retired because something better was available, or because the airframes were too tired for economical refurbishment?
Good questions. Even Taiwan's older Block 20 F-16As are more advanced than those stored earlier-Block F-16As. And, yes, additional, fully combat-capable F-16Vs would be much more desirable. Taipei has the money to go that route. The critical question is whether Xi will grant them the time to get through FMS approval process, new-airframe construction time, etc.
Here, we've been talking about a quickly-available air-intercept deterrent. I'm arguing that even early-model F-16A - appropriately stripped down to only that specialist role - can perform the interception role better than any kitted-up business jet (old or new). And those F-16As would be available to Taiwan much quicker than any new-build fighters.
Currently, the US seems motivated to push back against Beijing. That could translate into quick FMS approval for minimally tarted-up 'As. (Considering their anti-CPC rhetoric, Republicans in Congress would have a hard time saying 'no' to this request.) Taiwan gets interceptors quickly and, I'm betting, with more hours remaining on their airframes than the ROCAF's existing F-5E fleet.
When the time comes, leave the hard fighting to the Block 20s and 'Vs. Meanwhile plough even more hours onto those older Davis-Monthan airframes - as both LIFT and pure interceptors. Both roles serve to reduce Block 20 and F-16V flight-time (and, you could argue, 'cold war' intercepts are a natural extension of LIFT anyway). Alternatively, Taipei can gamble that they've got plenty of time to order up something shiny-new and ideal ...