Is this a joke? He wrote that he liked Arnold's and Wald's books. I have tried to study from typical physics undergrad books and was also missing some rigour wh

Is this a joke? He wrote that he liked Arnold's and Wald's books. I have tried to study from typical physics undergrad books and was also missing some rigour which I would assume most people coming from a math background would appreciate more in introductory physics books. Arnold's book or also Spivak's book are much better in that regard.