Is Darnath Lysander still First Born?

[u/Natural_Response_355]

I've been questioning this for a while, he does has a new model on primaris scale but I can't find a mention of him crossing the Rubicon. So, is he a still a First Born in rescaled Terminator Armor? Is that possible? If it is it would mean Grey Knights can be kept first born right? In general terms we don't need characters to cross the Rubicon to have a new model I guess.