It appears you've linked to a comment about the lack of a way to backup signal messages on iOS. That is separate(ish) from the importing of messages from WhatsApp.
So, no, they're not interested in WhatsApp import (per the closed ticket liked by the parent).
Additionally, the statement from signal is just PR spew. It boils down to "Nah, we won't make a way to do that.". The "privacy preserving" bit is nonsense because they have an export/import to a file on android.
Oh whoops, my bad - I was under the impression it was about import/export of Signal messages in general. There's been so much news about Signal recently that I'm getting comments mixed up, it seems.
So, no, they're not interested in WhatsApp import (per the closed ticket liked by the parent).
Additionally, the statement from signal is just PR spew. It boils down to "Nah, we won't make a way to do that.". The "privacy preserving" bit is nonsense because they have an export/import to a file on android.