I watched the interview and I’ll say the same thing again: he’s dodging the question because he’s not planning on carrying out those orders, but he doesn’t want to be fired

By admitting his plan to defy orders, he would be violating one of the central military laws; and will subsequently be fired. At which point, they could replace him with another Admiral willing to carry out those orders

Additionally, it could be considered as a breach of security. A plan to attack Canada would most certainly be a protected document, so mentioning there is a plan could be considered a breach. Again - he would be fired. (PS. All well established militaries have plans in the event of an invasion, regardless of the level of trust. It would be silly not to)