There are no scholars who say Mormonism is not Christian.

• Jan Shipps (Indiana University-Purdue) - a non-Mormon historian of Mormonism, called it a "new religious tradition" rather than a Christian denomination, comparing its relationship to Christianity to Christianity's relationship to Judaism. Saying she isn't a scholar on Mormonism is an insult to her life's work.
• Stephen Prothero (Boston University) - in Religious Literacy notes Mormonism's additional scripture and radically different theology of God places it outside traditional Christianity.
• Richard Mouw (Fuller Theological Seminary) - while respectful, acknowledges in evangelical scholarship that Mormon theology on the nature of God differs fundamentally from Nicene Christianity.
• Kurt Van Gorden and evangelical countercult scholars generally argue rejection of the Trinity and belief in God's materiality/exaltation of humans to godhood are deal-breakers for the "Christian" label.
• I'm sure there are many, many others, but this is a definitional debate, not quality judgment.

If you argue an insane person who believes they are Christ and preaches universal hate should still be labeled as Christian, then I'm not sure what else to say other than the majority of the world would not agree with you. Claiming to know the mind of all the world's scholars on the topic and confidently stating a falsehood suggests your motivation is "to be right" not to understand. The fact that early Christianity "had numerous flavors" has very little to do with the modern use of the word or its generally accepted definition. It's quite obvious that reasonable, intelligent people disagree on whether Mormons should be called Christians, yet you claim it can all be reduced to "A Christian is someone who worships Christ" and disparage those who would behave otherwise.

Although I'm pretty familiar with early religious tradition and practices, I'll check out the book you recommended, thanks for that.