They changed the deal on that once already by adjusting the eligibility time. We all agreed to them changing stuff when we ticked the EULA which is why they (rightly) didn't bother to consult the playerbase about Horizons going for free now.
Selling it in the store isn't really a serious proposition since they've always gone with cosmetics only and if you sell one ship people would want to buy others there. It sets a precedent with potential rear pain down the line like an exclusive ship.
Easier to roll it out to everyone, just like they have Horizons the DLC it was content for. Which they seem to be doing since the MK-IV featured in the promo. Plenty of ships to choose from, yet they went with that specific one.
Why make a change (to CIV availablility) at all though? Why not just do a different ship & make that exclusive too? Sell it in the shop even?
Forget the CIV, it's time has gone & anyone obsessing over the lack of access just can't accept the idea of exclusives. We could use more exclusive (non-meta) ships imo, just like we have loads of exclusive cosmetics.