US CTPP accession?

Trump's made some noises about seeking to join the CTPP agreement - after having pulled the US out of the TPPA negotiations. 

Should the CTPP countries let him in?

Recall that Trump's steel tariffs, from which Australia are exempt but New Zealand is not (or at least wasn't when last I checked) were justified on national security grounds. WTO Article XXI allows tariffs to protect industries critical for national security. The tariffs weren't put in place for national security. They were put in place for domestic political reasons or because of demons in Trump's head. But try proving that quickly or cheaply in a WTO dispute tribunal.

The CTPP has similar protections built in.

Article 29.2: Security Exceptions
Nothing in this Agreement shall be construed to:
(a) require a Party to furnish or allow access to any information the disclosure of which it determines to be contrary to its essential security interests; or
(b) preclude a Party from applying measures that it considers necessary for the fulfilment of its obligations with respect to the maintenance or restoration of international peace or security, or the protection of its own essential security interests.

These kinds of provisions (standard in trade agreements I believe) work among states that you can expect to behave like adults. The United States isn't like that currently. Why let them in? If they are admitted, what are the odds that Trump just invokes security exceptions again to undo whatever's negotiated?

There's risk we'll have eaten dead rats on copyright only for Trump to declare butter in need of protection for national security reasons.