The Real Reason Ash Tried To Kill Ripley With A Magazine In Alien
While the eponymous extraterrestrial is the primary villain in Ridley Scott's 1979 Science Fiction Horror classic "Alien," there's a secondary villain in the piece that serves as the monster's enabler and ally. That would be Ash (Ian Holm), the science officer of the USCSS Nostromo who turns out to be far more than he first appears. Initially Ash seems like a voice of reason among the crew: not as profit-minded as Parker (Yaphet Kotto) or Brett (Harry Dean Stanton), not as indecisive as Lambert (Veronica Cartwright), not as seemingly cold as Ripley (Sigourney Weaver) first appears, and not nearly as burnt out and going through the motions as Captain Dallas (Tom Skerritt). When Kane (John Hurt) is overtaken by the facehugger, Ripley wants to leave Dallas, Lambert, and Kane outside to maintain quarantine, but Ash chooses to let them inside in defiance of protocol, initially contrasting the pair as one seemingly cold-hearted pragmatist who's willing to cut losses, acting in her role as warrant officer, against a medical officer/scientist adhering to his principles in an effort to save lives.
By the movie's end this is all revealed to be a lie: Ash is in fact an android in the service of the Weyland-Yutani corporation, who receives orders to retrieve the alien lifeform from LV-426 at any cost: the Nostromo and her crew are declared "expendable" in the service of getting the creature to the company. When Ripley discovers the truth, Ash attempts to silence her in a truly horrifying manner.
A truly horrific act of violence
"Alien" is packed with moments of terror, but one that's decidedly intense and disturbing is when Ash attacks Ripley. Having learned the truth of just why the Nostromo was diverted to LV-426, Ripley quite rightly wants to tell Parker and Lambert, the only other two surviving members of the crew. Ash can't have her spoil the company's plans, so he attacks her, momentarily overpowering her and leaving her stunned. As she lies helpless, Ash rolls up one of the pornographic magazines in Parker and Brett's bunks and attempts to drive it down Ripley's throat. Thankfully he's stopped by Parker and Lambert's timely arrival, and the three are able to critically damage Ash before destroying him completely with a flamethrower.
Ash is revealed in the scene to be inhumanly strong, able to hold Parker at bay seemingly without effort. He easily could have overpowered Ripley, or simply snapped her neck. Why use the magazine?
Inside the mind of a machine gone mad
In various commentary tracks, as Screenrant points out, director Ridley Scott has speculated that Ash may well have been sexually attracted to Ripley, but as a machine lacked the understanding as well as the physical equipment to act on these drives. In this interpretation the magazine can be viewed as a metaphor for a sexual assault. While that's not clear from the original script by Dan O'Bannon, there may be another potential explanation: As Ash is a machine, the issue might be more one of programming than personal desire.
As an android, Ash was likely programmed to work to ensure human survival and safety, but when the orders came down to put the alien's life first and foremost, it put Ash into a state of internal conflict. Holm's face conveys this in a number of visual ticks during the scene, with Ash clearly being at war with his two conflicting directives: preserve the alien vs. preserving Ripley's life. Thus the choice of the magazine could be a way of absolving himself of the crime: he's not killing her directly, it's simply the magazine blocking the flow of air to her lungs.
Given Scott is the director and current steward of "Alien" canon, his interpretation is likely the one that was intended. But speculation and theorizing is one of the joys of fandom. In the end, art is subjective, and dependent on the interpretation of the audience.