Is it bad form to use he/she, he or she, or just he in the analysis of argument when referring to the author?

Typically I might have " the author concludes that......" somewhere later on I would say " he/she is assuming that...."

is this bad form? how to refer to the author then? Or is that a bad idea to begin with.

what about having the argument as the subject and then using the pronoun it " the argument suggests.." "it assumes that..."

thanks.