Someone is 'bad at their job' for not understanding the geopolitical inclinations of Vietnam?
These statements about Vietnam are out of context entirely.
We should be 'confused' that one would think 'the US should care more about the US than China' ... because that statement doesn't make any sense.
Vietnam 'cares' about other nations to the extent they have power, and that it affects them.
Nations in China's vicinity are very concerned about China's new Imperial ambitions, and it's been that way for centuries.
America et. al. are concerned about China's influence in neighbouring states.
The TPP is designed to provide economic synergy between those directly in the vicinity of China with the US + Canada + Australia so as to provide an economic basis and some degree of influence outside the direct purview of China.
In an interconnected world, small states are all in the orbit if larger states, it's as unavoidable as gravity.
Vietnam specifically is relatively small and weak, in order to gain leverage, they have to work with others with similar concerns i.e. Singapore, S. Korea, and having the US + Canada as a participant is a major bonus.
Vietnam was absolutely a willing and supportive proponent of the TPP for those reasons.
The 'deal killer' was not any Asian country, it was Trump, who foolishly thought it would be more advantageous for the US to deal with APAC States individually thereby gaining no leverage. While this would be true for individual trade concerns, it's completely short sighted vis-a-vis the bigger picture.