The way I read this thread, it comes across to me more as ubports made a post claiming it may cause delays/problems/whatever because they don’t want to overpromise. They have been told that there are no meaningful differences between the devkit and phone as shipped but I don’t expect they will redact/withdraw their statement and if pressured will ultimately stand by it on the grounds that if someone who gets the phone before them has issues they will be troubleshooting on different hardware that may result in a different experience.
This comes across to me less as a “we need the phone or this won’t work” and more as a "without a phone we may not be able to successfully troubleshoot an issue someone with the phone encounters.
It is an unknown, not a known negative.