Different scenario.
Marine ship docks to overrun refueling station, marines have to repair refueling station enough to refuel before their ship loses power. If they succeed they blow up station from a distance, if they fail their doors and defenses disable allowing xenos to board.
As a proud xeno main I believe that the complaints 'about Why aliens get free drop ship every time marins evac?' are unfounded. The xenos are extremely intelligent, thus they would have foresight into what a sophisticated military airship console would be like and how it would function, and with the nature of their evolutionary process would be perfectly able to pilot the ship down planet and dock perfectly on the landing pad.
All i hear here is mad Humie getteing mad about our superiour xeno roles, XD.
I'd be up for the removal of the ship finale for something more interesting since the "80 man retreat into slogging across the ship" meta gets really stale.
Maybe hold a point on the planet for X time, marines need to recover Y many things, or etc. Different game modes my dudes.
The real question is why do aliens not have their own dropship that is biological and can do biological weapon CAS runs on marines?