Grease is one of the last Classic Style Hollywood movie musicals. It is written and performed in the same vein as "Singing in the Rain", "Seven Brides for Seven Brothers" and "Bye-Bye Birdie". In this Musical Theater world, the thought of song and dance being a natural occurance is part of the suspension of dis-belief that accompanies all classic musical theater. This concept of any type of Death scenario just doesn't fit with the "Happy Sappy" style of this motion picture. I believe the reason we look at the theories presented here are that we are now fed a diet of "Realistic Universe" musicals where music is justified as a part of the characters lifestyles. Reference "The Blues Brothers" where the main characters are musicians and would naturally sing on a daily basis. Another example would be the "Sister Act" movies where any singing comes from a group of Nuns who sing as part of competition. Again the singing is a natural part of what they do. In today's musicals, we no longer see people breaking out in song because they're happy (reference Gene Kelly and Cyd Charrise in Brigadoon). Don't over think it, just enjoy the music and the 40 year old High Schoolers.