While I think Kanna would be well within her rights to tell Joe off, it seems to me like she's been waiting for him to take the initiative. Meanwhile Joe seems to have been stuck in the idea that he had to let her go back then, so he's got no right to reach out now. It would be nice to see two people who clearly still have those feelings for each other work it out somehow, even if either dropping their livelihood and crossing an ocean right away would be a tad one sided.
The ideal way it would work out, in my mind, is they have their big emotional conversation at the airport and Kanna still goes on her flight, but with the two of them actively planning for their future together (whichever side of the pacific they decide to have it in). I would also accept them hashing things out and agreeing it just wouldn't work, shaking hands and parting but with actual closure this time. However it turns out, Joe is providing Mitsuki a great example of how that attitude they share can lead to very sub-optimal outcomes.
