The nukes wouldn't be proliferated. They would merely be shuffled around.
1. It could be argued that Taiwan is not a recognized country.
2. Therefore, it could be argued that Taiwan belongs to either Red China or the US, both of which already have nuclear weapons.
3. Therefore, it could be argued that giving nukes to Taiwan is not proliferating them, since both the US and Red China have nukes already.
Okay, let's hear the argument that Taiwan belongs to the US. This should be good.