ThisIt does mention "unlock" - maybe, like the Imperial Clipper, the ship is not available to just anyone who enters the shipyard but requires a permit / rank to be able to be purchased. As long as the permit is able to be earned in-game in some way then that would seem to be fair enough to me.
"The Cobra Mk IV will be available in the game only to players who joined us in the first year – forever."
kinda contradicts that.
That said, anyone playing the game now (or getting into it this year) should be able to unlock the ship, if they are or become eligible for the Horizons expansion.