To my knwoledge, the Chi square test is corrected by Fisher’s exact test when the numbers are too smal or very unequally distributed among the cells of the table.

In addition, the variables whose p-value <0.25 as well as variables biologically plausible should be subjected to multivariable analysis (binary logistic regression) and the goodness of fit of the binary logistic regression model should be assessed by Hosmer and Lemeshow test.

Is the reviewer's argument correct? and if so how?