Despite enjoying wild popularity for much of its 12-season run on CBS, The Big Bang Theory drew criticism for its handling of social issues. Like many 2000s-2010s comedies, it was rife with contentious jokes; its women and characters of color were often stereotyped, and it portrayed disabled and neurodivergent characters in a way that, intentionally or not, could be harmful. Many of these issues are at the forefront of Season 2, Episode 17, "The Terminator Decoupling," which featured guest star Summer Glau as herself.
Glau rose to fame with her starring role as River Tam on Firefly, a sci-fi series referenced multiple times on The Big Bang Theory. In 2009, when "The Terminator Decoupling" was filmed, Glau starred as Cameron on Terminator: The Sarah Connor Chronicles, which -- like Big Bang -- was produced by Warner Bros. Television.
During Firefly's brief television run, River was deeply traumatized, and spent much of her time trying to remember how to be a person; her action-girl abilities were only revealed in the spinoff movie, Serenity. Similarly, Glau's role as the reprogrammed Terminator Cameron was primarily that of an action hero: She protected John Connor (Thomas Dekker) and his mother Sarah (Lena Headey) from other, often robotic, threats. Both of Glau's characters spoke in detached ways and processed emotions in manner that could be viewed as strange or off-putting.
Some of that manifested in how Glau's dialogue was written on The Big Bang Theory. In the episode, Leonard (Johnny Galecki), Sheldon (Jim Parsons), Raj (Kunal Nayyar) and Howard (Simon Helberg) are traveling from Los Angeles to San Francisco by train, at Sheldon's request. Sheldon is autistic-coded, although the writers later denied that he was written as such, and one example of this is his fixation with trains. While some autistic people are interested in trains, it has become a lazy writing shortcut.
The main characters soon discover Glau is also on the train, which sends them into a tizzy. Sheldon wonders if she is actually a Terminator, but otherwise doesn't engage with her. That's particularly strange, considering how intently he is known to pursue male celebrities when they cross his path. Howard, Leonard and Raj are all interested in talking to her, but they instead only discuss the possibility of hooking up with her.
Raj is the first to try, and gets a beer so he can talk to her. Like usual, his anxiety and selective mutism -- when "a person is unable to speak in certain social situations" are played for a joke. Raj's selective mutism flares up around women, unless he's intoxicated. In this episode, the joke is that, when Raj discovers his beer is non-alcoholic, he immediately clams up again. This suggests alcohol is more of a placebo, but also makes light of his condition.
After Raj strikes out, Howard takes his turn, and immediately makes unwanted sexual advances at Glau. He then talks her ear off, ignoring that Glau is uninterested and uncomfortable. Glau rebuffs Howard, but does agree to take a selfie with him; he later says she broke his camera after he continued to behave inappropriately. It is good that Howard wasn't rewarded for his bad behavior. Nevertheless, he sexually harasses her. The show, instead of discussing why this is unacceptable, plays it for a joke.
All of the gang display coded sexism toward Glau. In the case of Sheldon, he is not as interested in her as he typically would be in a male celebrity. For Raj and Howard, they see her more as a sexual object than a person. It is indicative of the problematic way The Big Bang Theory handled women in general: Female characters were rarely treated as equals, but instead objectified or used simply for cheap laughs.