Unless you're on the Board of Trustees, I'm not sure anyone conclusively knows why SMU attempted the split. It was clearly related to the 2019 General Conference, which, thanks to non-US churches and conferences, voted to maintain bans against LGBQT clergy and marriage.
Ironically, somewhat, that caused the schism under which "conservatives" left the UMC denomination, despite having "won."
When the BOT amended the Articles of Incorporation in 2019, SMU President Turner mentioned that LGBQT rights were protected, whatever that means. Supposedly, Bishop Scott Jones was one of the only dissenting votes to the amendment, and he was the sole Trustee that was actually affiliated with the governing body, the Southern Conference of the UMC.
And no, SMU is nothing like Baylor and never has been. The UMC has not been at all heavy-handed with the university and would never do shit like ban drinking or dancing on campus.