Warning! Spoilers ahead for Young Sheldon season 6.A lot of things are currently happening with the Coopers, but it's Young Sheldon season 6's most boring arc that's justifying a glaring The Big Bang Theory finale plot hole. Following an eventful Young Sheldon season 5, Sheldon and his family have been trying to get used to their new normal with Mandy and Georgie's arrangement as soon-to-be parents. Everyone else's storylines are impacted by the pair's situation, except Sheldon, who finally gets his own narrative after previously being relegated to a supporting role. Unfortunately, however, the boy genius' personal plot is also the most uninteresting story that's happening in Young Sheldon season 6.
Sheldon's conflict with Young Sheldon's new villain, East Texas Tech started when he came up with the idea for a grant database. Ever since the school realized its potential to be a lucrative venture, they have been trying to cash in on it. It took him a while, but Sheldon eventually saw this and cut them off; unfortunately, they aren't giving up, and instead doing everything they can to undermine the young genius. This arc is decently interesting, but considering everything else going on in Young Sheldon season 6, it's arguably the most boring storyline. However, it inadvertently helps another seemingly lacking narrative.
George and Mary were initially involved with the project because Sheldon is still a minor. The Cooper parents even hired a lawyer to go through the legal documents, but the proposed agreement didn't push through, hence Young Sheldon season 6's East Texas Tech conflict. Throughout his fight with his college, Sheldon barely gets any support from his family. In fact, all of them are seemingly oblivious to his personal challenges. This sets them apart from the Pasadena gang who were all supportive every single time Sheldon was in crisis in TBBT, especially when he encounters an issue with his Nobel Prize bid with Super Asymmetry.
This effectively justifies the Coopers' absence in The Big Bang Theory finale. As Sheldon reached his life-long dream of winning the Nobel Prize in Physics, there were questions about why none of his family were in attendance, but every single member of the Pasadena gang was there. The fact that they were never really involved with Sheldon's academic pursuits, as proven by Young Sheldon season 6, explains why he wasn't keen on ensuring their attendance in the Nobel Prize ceremony.
The Young Sheldon season 6 premiere supports the idea that Sheldon never saw his family as essential to his academic pursuits. However, aside from the narrative reason for the Coopers' absence in The Big Bang Theory finale, it was also a conscious decision from the creatives to not include them in the sendoff. While Sheldon clearly became its true lead as the sitcom went on, the show makers wanted to keep the focus on the Pasadena gang. In short, The Big Bang Theory finale was meant to celebrate the group's enduring friendship and how his friends essentially became Sheldon's second family. Bringing the Coopers in would distract from that.
CBS wanting to keep the focus on the Pasadena gang in the sitcom send-off, especially considering how much Sheldon's friends tolerated him in The Big Bang Theory is totally understandable. Seeing more of Sheldon's childhood in Young Sheldon, however, offers a better idea of how his relationship was with his family. While they aren't exactly involved with his scientific pursuits or studies in general, everyone is still very encouraging of him and they offer him support in any way that they can.
It's not a secret that Mary heavily favors the socially-inept genius among her kids and Young Sheldon proves that she has always been keen on catering to his needs. Meanwhile, Missy functions as his emotional support person. Both George and Georgie, on the other hand, work hard to ensure that everything he needs is provided to him. In fact, Georgie's The Big Bang Theory story about taking care of the family after the Cooper patriarch died should have been enough reason for him to be invited. So while they are unable to connect with Sheldon intellectually, they still contribute to Sheldon's growth as a person.
Young Sheldon season 6 airs Thursdays on CBS.